Method for performing v2x communication in wireless communication system and device for same

ABSTRACT

A method for performing vehicle-to-everything (V2X) communication in a wireless communication system and a device for same are disclosed. Particularly, a method for a user equipment (UE) performing V2X communication by means of a PC5 interface in a wireless communication system comprises the steps of: receiving from an upper layer a request for transmitting a V2X message; requesting radio resources, for V2X communication by means of a PC5 interface, to a base station or selecting radio resources for V2X communication by means of the PC5 interface; and performing transmission of V2X communication by means of the PC5 interface, wherein, if a UE has emergency packet data network (PDN) connection, an indication, indicating that transmission by means of the emergency PDN connection is a higher priority than the V2X communication by means of the PC5 interface, can be transmitted from the upper layer.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a wireless communication system, andmore particularly, to a method for performing/supportingvehicle-to-everything (V2X) communication and an apparatus forsupporting the same.

Related Art

Mobile communication systems have been developed to provide voiceservices, while guaranteeing user activity. Service coverage of mobilecommunication systems, however, has extended even to data services, aswell as voice services, and currently, an explosive increase in traffichas resulted in shortage of resource and user demand for a high speedservices, requiring advanced mobile communication systems.

The requirements of the next-generation mobile communication system mayinclude supporting huge data traffic, a remarkable increase in thetransfer rate of each user, the accommodation of a significantlyincreased number of connection devices, very low end-to-end latency, andhigh energy efficiency. To this end, various techniques, such as smallcell enhancement, dual connectivity, massive Multiple Input MultipleOutput (MIMO), in-band full duplex, non-orthogonal multiple access(NOMA), supporting super-wide band, and device networking, have beenresearched.

SUMMARY OF THE INVENTION

The present invention provides a method for performing V2X communicationover PC5 (a UE-to-UE radio interface/reference point) by a UE.

The present invention also provides a method for performing V2Xcommunication over PC5 by a UE which is in a limited service state.

The present invention also provides a method for processing bothtransmission over Uu (i.e., a radio interface/reference point between UEand eNB) and transmission over PC5.

The technical objects of the present invention are not limited to theaforementioned technical objects, and other technical objects, which arenot mentioned above, will be apparently appreciated by a person havingordinary skill in the art from the following description.

In an aspect of the present invention, a method for performing, by auser equipment (UE), vehicle-to-everything (V2X) communication over aPC5 interface in a wireless communication system includes: receiving arequest for transmitting a V2X message from an upper layer; requesting aradio resource for V2X communication to a base station via the PC5interface or selecting the radio resource for the V2X communication viathe PC5 interface; and performing transmission of the V2X communicationvia the PC5 interface, in which when the UE has an emergency packet datanetwork (PDN) connection, an indication that transmission through theemergency PDN connection takes priority over the V2X communication viathe PC5 interface may be forwarded from the upper layer.

In another aspect of the present invention, a user equipment (UE) forperforming vehicle-to-everything (V2X) communication over a PC5interface in a wireless communication system includes: a communicationmodule transmitting and receiving a wired/wireless signal; and aprocessor controlling the communication module, in which the processoris configured to receive a request for transmitting a V2X message froman upper layer, request a radio resource for V2X communication to a basestation via the PC5 interface or select the radio resource for the V2Xcommunication via the PC5 interface, and perform transmission of the V2Xcommunication via the PC5 interface, and when the UE has an emergencypacket data network (PDN) connection, an indication that transmissionthrough the emergency PDN connection takes priority over the V2Xcommunication via the PC5 interface is forwarded from the upper layer.

Preferably, the method may further include when the indication isreceived, preferentially processing the transmission through theemergency PDN connection over the transmission over the V2Xcommunication via the PC5 interface.

Preferably, the indication may be forwarded separately from a non-accessstratum (NAS) message for establishing the emergency PDN connection.

Preferably, the indication may be forwarded together with the non-accessstratum (NAS) message for establishing the emergency PDN connection.

Preferably, the request for transmitting the V2X message may include aV2X message, a V2X service identifier of a V2X service for the V2Xmessage, a data type in the V2X message, and a V2X message priority.

Preferably, when the UE is serviced by an Evolved Universal TerrestrialRadio Access Network (E-UTRAN), the UE intends to use the radio resourceprovided by a cell of the E-UTRAN, and a Public Land Mobile Network(PLMN) in which the UE is registered belongs to a PLMN list authorizedto use the V2X communication via the PC5, the radio resource for the V2Xcommunication via the PC5 interface may be requested to the basestation.

Preferably, when the UE is not serviced by the E-UTRAN and the UE isauthorized to use the V2X communication via the PC5, the radio resourcefor the V2X communication via the PC5 interface may be selected.

Preferably, when the UE is in an EPS Mobility Management (EMM)-IDLE modeand in a limited service state, the radio resource for the V2Xcommunication via the PC5 interface may be selected.

Preferably, an identifier of a bearer corresponding to the emergency PDNconnection may be forwarded together with the indication.

Preferably, only when the UE is in an EPS Mobility Management-CONNECTED(EMM) mode, the indication may be forwarded.

According to an embodiment of the present invention, even when a UE is,particularly, in a limited service state, the UE may perform V2Xcommunication. As a result, it is possible to cope with a load safetysituation or a public safety related situation.

Further, according to an embodiment of the present invention, when noerror occurs even in the case where transmission over Uu andtransmission of V2X communication over PC5 overlap with each other, itis possible to effectively treat overlapping together.

Advantages which can be obtained in the present invention are notlimited to the aforementioned effects and other unmentioned advantageswill be clearly understood by those skilled in the art from thefollowing description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the present invention and constitute a part ofspecifications of the present invention, illustrate embodiments of thepresent invention and together with the corresponding descriptions serveto explain the principles of the present invention.

FIG. 1 is a diagram schematically exemplifying an evolved packet system(EPS) to which the present invention can be applied.

FIG. 2 illustrates an example of evolved universal terrestrial radioaccess network structure to which the present invention can be applied.

FIG. 3 exemplifies a structure of E-UTRAN and EPC in a wirelesscommunication system to which the present invention can be applied.

FIG. 4 illustrates a structure of a radio interface protocol between aUE and E-UTRAN in a wireless communication system to which the presentinvention can be applied.

FIG. 5 is a diagram schematically showing a structure of a physicalchannel in a wireless communication system to which the presentinvention may be applied.

FIG. 6 is a diagram for describing a contention based random accessprocedure in a wireless communication system to which the presentinvention may be applied.

FIG. 7 is a diagram illustrating a sidelink UE information procedure ina wireless communication system to which the present invention may beapplied.

FIG. 8 is a diagram schematically exemplifying an attach procedure in awireless communication system to which the present invention may beapplied.

FIG. 9 illustrates an initial context setup procedure in a wirelesscommunication system to which the present invention may be applied.

FIG. 10 illustrates a UE context modification procedure in a wirelesscommunication system to which the present invention may be applied.

FIG. 11 illustrates a handover resource allocation procedure in awireless communication system to which the present invention may beapplied.

FIGS. 12 to 21 are diagrams illustrating a method for performing V2Xcommunication over PC5 according to an embodiment of the presentinvention.

FIG. 22 illustrates a block diagram of a communication apparatusaccording to an embodiment of the present invention.

FIG. 23 illustrates a block diagram of a communication apparatusaccording to an embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

In what follows, preferred embodiments according to the presentinvention will be described in detail with reference to appendeddrawings. The detailed descriptions provided below together withappended drawings are intended only to explain illustrative embodimentsof the present invention, which should not be regarded as the soleembodiments of the present invention. The detailed descriptions belowinclude specific information to provide complete understanding of thepresent invention. However, those skilled in the art will be able tocomprehend that the present invention may be embodied without thespecific information.

For some cases, to avoid obscuring the technical principles of thepresent invention, structures and devices well-known to the public maybe omitted or may be illustrated in the form of block diagrams utilizingfundamental functions of the structures and the devices.

A base station in this document is regarded as a terminal node of anetwork, which performs communication directly with a UE. In thisdocument, particular operations regarded to be performed by the basestation may be performed by an upper node of the base station dependingon situations. In other words, it is apparent that in a networkconsisting of a plurality of network nodes including a base station,various operations performed for communication with a UE may beperformed by the base station or by network nodes other than the basestation. The term Base Station (BS) may be replaced with a fixedstation, Node B, evolved-NodeB (eNB), Base Transceiver System (BTS), orAccess Point (AP). Also, a terminal may be fixed or mobile; and the termmay be replaced with User Equipment (UE), Mobile Station (MS), UserTerminal (UT), Mobile Subscriber Station (MSS), Subscriber Station (SS),Advanced Mobile Station (AMS), Wireless Terminal (WT), Machine-TypeCommunication (MTC) device, Machine-to-Machine (M2M) device, orDevice-to-Device (D2D) device.

In what follows, downlink (DL) refers to communication from a basestation to a terminal, while uplink (UL) refers to communication from aterminal to a base station. In downlink transmission, a transmitter maybe part of the base station, and a receiver may be part of the terminal.Similarly, in uplink transmission, a transmitter may be part of theterminal, and a receiver may be part of the base station.

Specific terms used in the following descriptions are introduced to helpunderstanding the present invention, and the specific terms may be usedin different ways as long as it does not leave the technical scope ofthe present invention.

The technology described below may be used for various types of wirelessaccess systems based on Code Division Multiple Access (CDMA), FrequencyDivision Multiple Access (FDMA), Time Division Multiple Access (TDMA),Orthogonal Frequency Division Multiple Access (OFDMA), Single CarrierFrequency Division Multiple Access (SC-FDMA), or Non-Orthogonal MultipleAccess (NOMA). CDMA may be implemented by such radio technology asUniversal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may beimplemented by such radio technology as Global System for Mobilecommunications (GSM), General Packet Radio Service (GPRS), or EnhancedData rates for GSM Evolution (EDGE). 01-DMA may be implemented by suchradio technology as the IEEE 802.11 (Wi-Fi), the IEEE 802.16 (WiMAX),the IEEE 802-20, or Evolved UTRA (E-UTRA). UTRA is part of the UniversalMobile Telecommunications System (UMTS). The 3rd Generation PartnershipProject (3GPP) Long Term Evolution (LTE) is part of the Evolved UMTS(E-UMTS) which uses the E-UTRA, employing OFDMA for downlink and SC-FDMAfor uplink transmission. The LTE-A (Advanced) is an evolved version ofthe 3GPP LTE system.

Embodiments of the present invention may be supported by standarddocuments disclosed in at least one of wireless access systems includingthe IEEE 802, 3GPP, and 3GPP2 specifications. In other words, among theembodiments of the present invention, those steps or parts omitted forthe purpose of clearly describing technical principles of the presentinvention may be supported by the documents above. Also, all of theterms disclosed in this document may be explained with reference to thestandard documents.

To clarify the descriptions, this document is based on the 3GPPLTE/LTE-A, but the technical features of the present invention are notlimited to the current descriptions.

Terms used in this document are defined as follows.

-   -   Universal Mobile Telecommunication System (UMTS): the 3rd        generation mobile communication technology based on GSM,        developed by the 3GPP    -   Evolved Packet System (EPS): a network system comprising an        Evolved Packet Core (EPC), a packet switched core network based        on the Internet Protocol (IP) and an access network such as the        LTE and UTRAN. The EPS is a network evolved from the UMTS.    -   NodeB: the base station of the UMTS network. NodeB is installed        outside and provides coverage of a macro cell.    -   eNodeB: the base station of the EPS network. eNodeB is installed        outside and provides coverage of a macro cell.    -   User Equipment (UE): A UE may be called a terminal, Mobile        Equipment (ME), or Mobile Station (MS). A UE may be a portable        device such as a notebook computer, mobile phone, Personal        Digital Assistant (PDA), smart phone, or a multimedia device; or        a fixed device such as a Personal Computer (PC) or        vehicle-mounted device. The term UE may refer to an MTC terminal        in the description related to MTC.    -   IP Multimedia Subsystem (IMS): a sub-system providing multimedia        services based on the IP    -   International Mobile Subscriber Identity (IMSI): a globally        unique subscriber identifier assigned in a mobile communication        network    -   Machine Type Communication (MTC): communication performed by        machines without human intervention. It may be called        Machine-to-Machine (M2M) communication.    -   MTC terminal (MTC UE or MTC device): a terminal (for example, a        vending machine, meter, and so on) equipped with a communication        function operating through a mobile communication network (For        example, communicating with an MTC server via a PLMN) and        performing an MTC function    -   MTC server: a server on a network managing MTC terminals. It may        be installed inside or outside a mobile communication network.        It may provide an interface through which an MTC user may access        the server. Also, an MTC server may provide MTC-related services        to other servers (in the form of Services Capability Server        (SCS)) or the MTC server itself may be an MTC Application        Server.    -   (MTC) application: services (to which MTC is applied) (for        example, remote metering, traffic movement tracking, weather        observation sensors, and so on)    -   (MTC) Application Server: a server on a network in which (MTC)        applications are performed    -   MTC feature: a function of a network to support MTC        applications. For example, MTC monitoring is a feature intended        to prepare for loss of a device in an MTC application such as        remote metering, and low mobility is a feature intended for an        MTC application with respect to an MTC terminal such as a        vending machine.    -   MTC User (MTC User): The MTC user uses the service provided by        the MTC server.    -   MTC subscriber: an entity having a connection relationship with        a network operator and providing services to one or more MTC        terminals.    -   MTC group: an MTC group shares at least one or more MTC features        and denotes a group of MTC terminals belonging to MTC        subscribers.    -   Services Capability Server (SCS): an entity being connected to        the 3GPP network and used for communicating with an MTC        InterWorking Function (MTC-IWF) on a Home PLMN (HPLMN) and an        MTC terminal. The SCS provides the capability for use by one or        more MTC applications.    -   External identifier: a globally unique identifier used by an        external entity (for example, an SCS or an Application Server)        of the 3GPP network to indicate (or identify) an MTC terminal        (or a subscriber to which the MTC terminal belongs). An external        identifier includes a domain identifier and a local identifier        as described below.    -   Domain identifier: an identifier used for identifying a domain        in the control region of a mobile communication network service        provider. A service provider may use a separate domain        identifier for each service to provide an access to a different        service.    -   Local identifier: an identifier used for deriving or obtaining        an International Mobile Subscriber Identity (IMSI). A local        identifier should be unique within an application domain and is        managed by a mobile communication network service provider.    -   Radio Access Network (RAN): a unit including a Node B, a Radio        Network Controller (RNC) controlling the Node B, and an eNodeB        in the 3GPP network. The RAN is defined at the terminal level        and provides a connection to a core network.    -   Home Location Register (HLR)/Home Subscriber Server (HSS): a        database provisioning subscriber information within the 3GPP        network. An HSS may perform functions of configuration storage,        identity management, user state storage, and so on.    -   RAN Application Part (RANAP): an interface between the RAN and a        node in charge of controlling a core network (in other words, a        Mobility Management Entity (MME)/Serving GPRS (General Packet        Radio Service) Supporting Node (SGSN)/Mobile Switching Center        (MSC)).    -   Public Land Mobile Network (PLMN): a network formed to provide        mobile communication services to individuals. The PLMN may be        formed separately for each operator.    -   Service Capability Exposure Function (SCEF): An entity within        the 3GPP architecture for service capability exposure that        provides a means for securely exposing services and capabilities        provided by 3GPP network interfaces.

In what follows, the present invention will be described based on theterms defined above.

Overview of System to which the Present Invention May be Applied

FIG. 1 illustrates an Evolved Packet System (EPS) to which the presentinvention may be applied.

The network structure of FIG. 1 is a simplified diagram restructuredfrom an Evolved Packet System (EPS) including Evolved Packet Core (EPC).

The EPC is a main component of the System Architecture Evolution (SAE)intended for improving performance of the 3GPP technologies. SAE is aresearch project for determining a network structure supporting mobilitybetween multiple heterogeneous networks. For example, SAE is intended toprovide an optimized packet-based system which supports various IP-basedwireless access technologies, provides much more improved datatransmission capability, and so on.

More specifically, the EPC is the core network of an IP-based mobilecommunication system for the 3GPP LTE system and capable of supportingpacket-based real-time and non-real time services. In the existingmobile communication systems (namely, in the 2nd or 3rd mobilecommunication system), functions of the core network have beenimplemented through two separate sub-domains: a Circuit-Switched (CS)sub-domain for voice and a Packet-Switched (PS) sub-domain for data.However, in the 3GPP LTE system, an evolution from the 3rd mobilecommunication system, the CS and PS sub-domains have been unified into asingle IP domain. In other words, in the 3GPP LTE system, connectionbetween UEs having IP capabilities may be established through anIP-based base station (for example, eNodeB), EPC, and application domain(for example, IMS). In other words, the EPC provides the architectureessential for implementing end-to-end IP services.

The EPC includes various components, where FIG. 1 illustrates part ofthe EPC components, including a Serving Gateway (SGW or S-GW), PacketData Network Gateway (PDN GW or PGW or P-GW), Mobility Management Entity(MME), Serving GPRS Supporting Node (SGSN), and enhanced Packet DataGateway (ePDG).

The SGW operates as a boundary point between the Radio Access Network(RAN) and the core network and maintains a data path between the eNodeBand the PDN GW. Also, if UE moves across serving areas by the eNodeB,the SGW acts as an anchor point for local mobility. In other words,packets may be routed through the SGW to ensure mobility within theE-UTRAN (Evolved-UMTS (Universal Mobile Telecommunications System)Terrestrial Radio Access Network defined for the subsequent versions ofthe 3GPP release 8). Also, the SGW may act as an anchor point formobility between the E-UTRAN and other 3GPP networks (the RAN definedbefore the 3GPP release 8, for example, UTRAN or GERAN (GSM (GlobalSystem for Mobile Communication)/EDGE (Enhanced Data rates for GlobalEvolution) Radio Access Network).

The PDN GW corresponds to a termination point of a data interface to apacket data network. The PDN GW may support policy enforcement features,packet filtering, charging support, and so on. Also, the PDN GW may actas an anchor point for mobility management between the 3GPP network andnon-3GPP networks (for example, an unreliable network such as theInterworking Wireless Local Area Network (I-WLAN) or reliable networkssuch as the Code Division Multiple Access (CDMA) network and WiMax).

In the example of a network structure as shown in FIG. 1, the SGW andthe PDN GW are treated as separate gateways; however, the two gatewaysmay be implemented according to single gateway configuration option.

The MME performs signaling for the UE's access to the network,supporting allocation, tracking, paging, roaming, handover of networkresources, and so on; and control functions. The MME controls controlplane functions related to subscribers and session management. The MMEmanages a plurality of eNodeBs and performs signaling of theconventional gateway's selection for handover to other 2G/3G networks.Also, the MME performs such functions as security procedures,terminal-to-network session handling, idle terminal location management,and so on.

The SGSN deals with all kinds of packet data including the packet datafor mobility management and authentication of the user with respect toother 3GPP networks (for example, the GPRS network).

The ePDG acts as a security node with respect to an unreliable, non-3GPPnetwork (for example, I-WLAN, WiFi hotspot, and so on).

As described with respect to FIG. 1, a UE with the IP capability mayaccess the IP service network (for example, the IMS) that a serviceprovider (namely, an operator) provides, via various components withinthe EPC based not only on the 3GPP access but also on the non-3GPPaccess.

Also, FIG. 1 illustrates various reference points (for example, S1-U,S1-MME, and so on). The 3GPP system defines a reference point as aconceptual link which connects two functions defined in disparatefunctional entities of the E-UTAN and the EPC. Table 1 below summarizesreference points shown in FIG. 1. In addition to the examples of FIG. 1,various other reference points may be defined according to networkstructures.

TABLE 1 reference point Description S1-MME Reference point for thecontrol plane protocol between E-UTRAN and MME S1-U Reference pointbetween E-UTRAN and Serving GW for the per bearer user plane tunnelingand inter eNodeB path switching during handover S3 It enables user andbearer information exchange for inter 3GPP access network mobility inidle and/or active state. This reference point may be used intra-PLMN orinter-PLMN (e.g. in the case of Inter-PLMN HO). S4 It provides relatedcontrol and mobility support between GPRS core and the 3GPP anchorfunction of Serving GW. In addition, if direct tunnel is notestablished, it provides the user plane tunneling. S5 It provides userplane tunneling and tunnel management between Serving GW and PDN GW. Itis used for Serving GW relocation due to UE mobility if the Serving GWneeds to connect to a non-collocated PDN GW for the required PDNconnectivity. S11 Reference point for the control plane protocol betweenMME and SGW SGi It is the reference point between the PDN GW and thepacket data network. Packet data network may be an operator externalpublic or private packet data network or an intra-operator packet datanetwork (e.g., for provision of IMS services). This reference pointcorresponds to Gi for 3GPP accesses.

Among the reference points shown in FIG. 1, S2a and S2b corresponds tonon-3GPP interfaces. S2a is a reference point which provides reliable,non-3GPP access, related control between PDN GWs, and mobility resourcesto the user plane. S2b is a reference point which provides relatedcontrol and mobility resources to the user plane between ePDG and PDNGW.

FIG. 2 illustrates one example of an Evolved Universal Terrestrial RadioAccess Network (E-UTRAN) to which the present invention may be applied.

The E-UTRAN system is an evolved version of the existing UTRAN system,for example, and is also referred to as 3GPP LTE/LTE-A system.Communication network is widely deployed in order to provide variouscommunication services such as voice (e.g., Voice over Internet Protocol(VoIP)) through IMS and packet data.

Referring to FIG. 2, E-UMTS network includes E-UTRAN, EPC and one ormore UEs. The E-UTRAN includes eNBs that provide control plane and userplane protocol, and the eNBs are interconnected with each other by meansof the X2 interface.

The X2 user plane interface (X2-U) is defined among the eNBs. The X2-Uinterface provides non-guaranteed delivery of the user plane Packet DataUnit (PDU). The X2 control plane interface (X2-CP) is defined betweentwo neighboring eNBs. The X2-CP performs the functions of contextdelivery between eNBs, control of user plane tunnel between a source eNBand a target eNB, delivery of handover-related messages, uplink loadmanagement, and so on.

The eNB is connected to the UE through a radio interface and isconnected to the Evolved Packet Core (EPC) through the S1 interface.

The S1 user plane interface (S1-U) is defined between the eNB and theServing Gateway (S-GW). The S1 control plane interface (S1-MME) isdefined between the eNB and the Mobility Management Entity (MME). The S1interface performs the functions of EPS bearer service management,non-access stratum (NAS) signaling transport, network sharing, MME loadbalancing management, and so on. The S1 interface supportsmany-to-many-relation between the eNB and the MME/S-GW.

The MME may perform various functions such as NAS signaling security,Access Stratum (AS) security control, Core Network (CN) inter-nodesignaling for supporting mobility between 3GPP access network, IDLE modeUE reachability (including performing paging retransmission andcontrol), Tracking Area Identity (TAI) management (for UEs in idle andactive mode), selecting PDN GW and SGW, selecting MME for handover ofwhich the MME is changed, selecting SGSN for handover to 2G or 3G 3GPPaccess network, roaming, authentication, bearer management functionincluding dedicated bearer establishment, Public Warning System (PWS)(including Earthquake and Tsunami Warning System (ETWS) and CommercialMobile Alert System (CMAS), supporting message transmission and so on.

FIG. 3 exemplifies a structure of E-UTRAN and EPC in a wirelesscommunication system to which the present invention may be applied.

Referring to FIG. 3, an eNB may perform functions of selecting gateway(e.g., MME), routing to gateway during radio resource control (RRC) isactivated, scheduling and transmitting broadcast channel (BCH), dynamicresource allocation to UE in uplink and downlink, mobility controlconnection in LTE_ACTIVE state. As described above, the gateway in EPCmay perform functions of paging origination, LTE_IDLE state management,ciphering of user plane, bearer control of System Architecture Evolution(SAE), ciphering of NAS signaling and integrity protection.

FIG. 4 illustrates a radio interface protocol structure between a UE andan E-UTRAN in a wireless communication system to which the presentinvention may be applied.

FIG. 4(a) illustrates a radio protocol structure for the control plane,and FIG. 4(b) illustrates a radio protocol structure for the user plane.

Referring to FIG. 4, layers of the radio interface protocol between theUE and the E-UTRAN may be divided into a first layer (L1), a secondlayer (L2), and a third layer (L3) based on the lower three layers ofthe Open System Interconnection (OSI) model, widely known in thetechnical field of communication systems. The radio interface protocolbetween the UE and the E-UTRAN consists of the physical layer, data linklayer, and network layer in the horizontal direction, while in thevertical direction, the radio interface protocol consists of the userplane, which is a protocol stack for delivery of data information, andthe control plane, which is a protocol stack for delivery of controlsignals.

The control plane acts as a path through which control messages used forthe UE and the network to manage calls are transmitted. The user planerefers to the path through which the data generated in the applicationlayer, for example, voice data, Internet packet data, and so on aretransmitted. In what follows, described will be each layer of thecontrol and the user plane of the radio protocol.

The physical layer (PHY), which is the first layer (L1), providesinformation transfer service to upper layers by using a physicalchannel. The physical layer is connected to the Medium Access Control(MAC) layer located at the upper level through a transport channelthrough which data are transmitted between the MAC layer and thephysical layer. Transport channels are classified according to how andwith which features data are transmitted through the radio interface.And data are transmitted through the physical channel between differentphysical layers and between the physical layer of a transmitter and thephysical layer of a receiver. The physical layer is modulated accordingto the Orthogonal Frequency Division Multiplexing (OFDM) scheme andemploys time and frequency as radio resources.

A few physical control channels are used in the physical layer. ThePhysical Downlink Control Channel (PDCCH) informs the UE of resourceallocation of the Paging Channel (PCH) and the Downlink Shared Channel(DL-SCH); and Hybrid Automatic Repeat reQuest (HARQ) information relatedto the Uplink Shared Channel (UL-SCH). Also, the PDCCH may carry a ULgrant used for informing the UE of resource allocation of uplinktransmission. The Physical Control Format Indicator Channel (PCFICH)informs the UE of the number of OFDM symbols used by PDCCHs and istransmitted at each subframe. The Physical HARQ Indicator Channel(PHICH) carries a HARQ ACK (ACKnowledge)/NACK (Non-ACKnowledge) signalin response to uplink transmission. The Physical Uplink Control Channel(PUCCH) carries uplink control information such as HARQ ACK/NACK withrespect to downlink transmission, scheduling request, Channel QualityIndicator (CQI), and so on. The Physical Uplink Shared Channel (PUSCH)carries the UL-SCH.

The MAC layer of the second layer (L2) provides a service to the RadioLink Control (RLC) layer, which is an upper layer thereof, through alogical channel. Also, the MAC layer provides a function of mappingbetween a logical channel and a transport channel; andmultiplexing/demultiplexing a MAC Service Data Unit (SDU) belonging tothe logical channel to the transport block, which is provided to aphysical channel on the transport channel.

The RLC layer of the second layer (L2) supports reliable datatransmission. The function of the RLC layer includes concatenation,segmentation, reassembly of the RLC SDU, and so on. To satisfy varyingQuality of Service (QoS) requested by a Radio Bearer (RB), the RLC layerprovides three operation modes: Transparent Mode (TM), UnacknowledgedMode (UM), and Acknowledge Mode (AM). The AM RLC provides errorcorrection through Automatic Repeat reQuest (ARQ). Meanwhile, if MAClayer performs the RLC function, the RLC layer may be incorporated intothe MAC layer as a functional block.

The Packet Data Convergence Protocol (PDCP) layer of the second layer(L2) performs the function of delivering, header compression, cipheringof user data in the user plane, and so on. Header compression refers tothe function of reducing the size of the Internet Protocol (IP) packetheader which is relatively large and contains unnecessary control toefficiently transmit IP packets such as the IPv4 (Internet Protocolversion 4) or IPv6 (Internet Protocol version 6) packets through a radiointerface with narrow bandwidth. The function of the PDCP layer in thecontrol plane includes delivering control plane data andciphering/integrity protection.

The Radio Resource Control (RRC) layer in the lowest part of the thirdlayer (L3) is defined only in the control plane. The RRC layer performsthe role of controlling radio resources between the UE and the network.To this purpose, the UE and the network exchange RRC messages throughthe RRC layer. The RRC layer controls a logical channel, transportchannel, and physical channel with respect to configuration,re-configuration, and release of radio bearers. A radio bearer refers toa logical path that the second layer (L2) provides for data transmissionbetween the UE and the network. Configuring a radio bearer indicatesthat characteristics of a radio protocol layer and channel are definedto provide specific services; and each individual parameter andoperating methods thereof are determined. Radio bearers may be dividedinto Signaling Radio Bearers (SRBs) and Data RBs (DRBs). An SRB is usedas a path for transmitting an RRC message in the control plane, while aDRB is used as a path for transmitting user data in the user plane.

The Non-Access Stratum (NAS) layer in the upper of the RRC layerperforms the function of session management, mobility management, and soon.

A cell constituting the base station is set to one of 1.25, 2.5, 5, 10,and 20 MHz bandwidth, providing downlink or uplink transmission servicesto a plurality of UEs. Different cells may be set to differentbandwidths.

Downlink transport channels transmitting data from a network to a UEinclude a Broadcast Channel (BCH) transmitting system information, PCHtransmitting paging messages, DL-SCH transmitting user traffic orcontrol messages, and so on. Traffic or a control message of a downlinkmulti-cast or broadcast service may be transmitted through the DL-SCH orthrough a separate downlink Multicast Channel (MCH). Meanwhile, uplinktransport channels transmitting data from a UE to a network include aRandom Access Channel (RACH) transmitting the initial control messageand a Uplink Shared Channel (UL-SCH) transmitting user traffic orcontrol messages.

Logical channels, which are located above the transport channels and aremapped to the transport channels. The logical channels may bedistinguished by control channels for delivering control areainformation and traffic channels for delivering user area information.The control channels include a Broadcast Control Channel (BCCH), aPaging Control Channel (PCCH), a Common Control Channel (CCCH), adedicated control channel (DCCH), a Multicast Control Channel (MCCH),and etc. The traffic channels include a dedicated traffic channel(DTCH), and a Multicast Traffic Channel (MTCH), etc. The PCCH is adownlink channel that delivers paging information, and is used whennetwork does not know the cell where a UE belongs. The CCCH is used by aUE that does not have RRC connection with network. The MCCH is apoint-to-multipoint downlink channel which is used for deliveringMultimedia Broadcast and Multicast Service (MBMS) control informationfrom network to UE. The DCCH is a point-to-point bi-directional channelwhich is used by a UE that has RRC connection delivering dedicatedcontrol information between UE and network. The DTCH is a point-to-pointchannel which is dedicated to a UE for delivering user information thatmay be existed in uplink and downlink. The MTCH is a point-to-multipointdownlink channel for delivering traffic data from network to UE.

In case of uplink connection between the logical channel and thetransport channel, the DCCH may be mapped to UL-SCH, the DTCH may bemapped to UL-SCH, and the CCCH may be mapped to UL-SCH. In case ofdownlink connection between the logical channel and the transportchannel, the BCCH may be mapped to BCH or DL-SCH, the PCCH may be mappedto PCH, the DCCH may be mapped to DL-SCH, the DTCH may be mapped toDL-SCH, the MCCH may be mapped to MCH, and the MTCH may be mapped toMCH.

FIG. 5 is a diagram schematically exemplifying a structure of physicalchannel in a wireless communication system to which the presentinvention may be applied.

Referring to FIG. 5, the physical channel delivers signaling and datathrough radio resources including one or more subcarriers in frequencydomain and one or more symbols in time domain.

One subframe that has a length of 1.0 ms includes a plurality ofsymbols. A specific symbol (s) of subframe (e.g., the first symbol ofsubframe) may be used for PDCCH. The PDCCH carries information forresources which are dynamically allocated (e.g., resource block,modulation and coding scheme (MCS), etc.).

Random Access Procedure

Hereinafter, a random access procedure which is provided in a LTE/LTE-Asystem will be described.

The random access procedure is performed in case that the UE performs aninitial access in a RRC idle state without any RRC connection to an eNB,or the UE performs a RRC connection re-establishment procedure, etc.

The LTE/LTE-A system provides both of the contention-based random accessprocedure that the UE randomly selects to use one preamble in a specificset and the non-contention-based random access procedure that the eNBuses the random access preamble that is allocated to a specific UE.

FIG. 6 is a diagram for describing the contention-based random accessprocedure in the wireless communication system to which the presentinvention may be applied.

(1) Message 1 (Msg 1)

First, the UE randomly selects one random access preamble (RACHpreamble) from the set of the random access preamble that is instructedthrough system information or handover command, selects and transmitsphysical RACH (PRACH) resource which is able to transmit the randomaccess preamble.

The eNB that receives the random access preamble from the UE decodes thepreamble and acquires RA-RNTI. The RA-RNTI associated with the PRACH towhich the random access preamble is transmitted is determined accordingto the time-frequency resource of the random access preamble that istransmitted by the corresponding UE.

(2) Message 2 (Msg 2)

The eNB transmits the random access response that is addressed toRA-RNTI that is acquired through the preamble on the Msg 1 to the UE.The random access response may include RA preamble index/identifier, ULgrant that informs the UL radio resource, temporary cell RNTI (TC-RNTI),and time alignment command (TAC). The TAC is the information indicatinga time synchronization value that is transmitted by the eNB in order tokeep the UL time alignment. The UE renews the UL transmission timingusing the time synchronization value. On the renewal of the timesynchronization value, the UE renews or restarts the time alignmenttimer. The UL grant includes the UL resource allocation that is used fortransmission of the scheduling message to be described later (Message 3)and the transmit power command (TPC). The TCP is used for determinationof the transmission power for the scheduled PUSCH.

The UE, after transmitting the random access preamble, tries to receivethe random access response of its own within the random access responsewindow that is instructed by the eNB with system information or handovercommand, detects the PDCCH masked with RA-RNTI that corresponds toPRACH, and receives the PDSCH that is indicated by the detected PDCCH.The random access response information may be transmitted in a MACpacket data unit and the MAC PDU may be delivered through PDSCH.

The UE terminates monitoring of the random access response ifsuccessfully receiving the random access response having the randomaccess preamble index/identifier same as the random access preamble thatis transmitted to the eNB. Meanwhile, if the random access responsemessage has not been received until the random access response window isterminated, or if not received a valid random access response having therandom access preamble index same as the random access preamble that istransmitted to the eNB, it is considered that the receipt of randomaccess response is failed, and after that, the UE may perform theretransmission of preamble.

(3) Message 3 (Msg 3)

In case that the UE receives the random access response that iseffective with the UE itself, the UE processes the information includedin the random access response respectively. That is, the UE applies TACand stores TC-RNTI. Also, by using UL grant, the UE transmits the datastored in the buffer of UE or the data newly generated to the eNB.

In case of the initial access of UE, the RRC connection request that isdelivered through CCCH after generating in RRC layer may be transmittedwith being included in the message 3. In case of the RRC connectionreestablishment procedure, the RRC connection reestablishment requestthat is delivered through CCCH after generating in RRC layer may betransmitted with being included in the message 3. Additionally, NASaccess request message may be included.

The message 3 should include the identifier of UE. There are two wayshow to include the identifier of UE. The first method is that the UEtransmits the cell RNTI (C-RNTI) of its own through the UL transmissionsignal corresponding to the UL grant, if the UE has a valid C-RNTI thatis already allocated by the corresponding cell before the random accessprocedure. Meanwhile, if the UE has not been allocated a valid C-RNTIbefore the random access procedure, the UE transmits including uniqueidentifier of its own (for example, SAE temporary mobile subscriberidentity (S-TMSI) or random number). Normally the above uniqueidentifier is longer that C-RNTI.

If transmitting the data corresponding to the UL grant, the UE initiatesa contention resolution timer.

(4) Message 4 (Msg 4)

The eNB, in case of receiving the C-RNTI of corresponding UE through themessage 3 from the UE, transmits the message 4 to the UE by using thereceived C-RNTI. Meanwhile, in case of receiving the unique identifier(that is, S-TMSI or random number) through the message 3 from the UE,the eNB transmits the 4 message to the UE by using the TC-RNTI that isallocated from the random access response to the corresponding UE. Forexample, the 4 message may include the RRC connection setup message.

The UE waits for the instruction of eNB for collision resolution aftertransmitting the data including the identifier of its own through the ULgrant included the random access response. That is, the UE attempts thereceipt of PDCCH in order to receive a specific message. There are twoways how to receive the PDCCH. As previously mentioned, in case that themessage 3 transmitted in response to the UL grant includes C-RNTI as anidentifier of its own, the UE attempts the receipt of PDCCH using theC-RNTI of itself, and in case that the above identifier is the uniqueidentifier (that is, S-TMSI or random number), the UE tries to receivePDCCH using the TC-RNTI that is included in the random access response.After that, in the former case, if the PDCCH is received through theC-RNTI of its own before the contention resolution timer is terminated,the UE determines that the random access procedure is performed andterminates the procedure. In the latter case, if the PDCCH is receivedthrough the TC-RNTI before the contention resolution timer isterminated, the UE checks on the data that is delivered by PDSCH, whichis addressed by the PDCCH. If the content of the data includes theunique identifier of its own, the UE terminates the random accessprocedure determining that a normal procedure has been performed. The UEacquires C-RNTI through the 4 message, and after that, the UE andnetwork are to transmit and receive a UE-specific message by using theC-RNTI.

Meanwhile, the operation of the non-contention-based random accessprocedure, unlike the contention-based random access procedureillustrated in FIG. 11, is terminated with the transmission of message 1and message 2 only. However, the UE is going to be allocated a randomaccess preamble from the eNB before transmitting the random accesspreamble to the eNB as the message 1. And the UE transmits the allocatedrandom access preamble to the eNB as the message 1, and terminates therandom access procedure by receiving the random access response from theeNB.

Terms used in this specification are described below.

-   -   Dedicated bearer: an EPS bearer associated with an uplink packet        filter(s) within a UE and a downlink packet filter(s) within a        P-GW. In this case, only a specific packet is matched with the        filter(s).    -   Default bearer: an EPS bearer established even new PDN        connection. Context of a default bearer is maintained during the        lifetime of a PDN connection.    -   EPS mobility management (EMM)-EMM-NULL state: an EPS service        within a UE is deactivated. Any EPS mobility management function        is not performed.    -   EMM-DEREGISTERED state: in the EMM-DEREGISTERED state, EMM        context is not established and an MME is not notified of a UE        location. Accordingly, the UE is unreachable by the MME. In        order to establish EMM context, the UE needs to start an Attach        or combined Attach procedure.    -   EMM-REGISTERED state: In the EMM-REGISTERED state, EMM context        within a UE has been established and default EPS bearer context        has been activated. When a UE is in the EMM-IDLE mode, an MME is        notified of a UE location with accuracy of a list of TAs        including a specific number of a TA. The UE may initiate the        transmission and reception of user data and signaling        information and may respond to paging. Furthermore, a TAU or        combined TAU procedure is performed.    -   EMM-CONNECTED mode: when an NAS signaling connection is set up        between a UE and a network, the UE is the EMM-CONNECTED mode.        The term “EMM-CONNECTED” may be referred to as a term        “ECM-CONNECTED state.”    -   EMM-IDLE mode: when an NAS signaling connection is not present        between a UE and a network (i.e., an EMM-IDLE mode without        suspend indication) or RRC connection suspend is indicated by a        lower layer (i.e., an EMM-IDLE mode with suspend indication),        the UE is in the EMM-IDLE mode. The term “EMM-IDLE” may be        referred to as a term “ECM-IDLE state.”    -   EMM context: when an Attach procedure is successfully completed,        EMM context is established between a UE and an MME.    -   Control plane CIoT EPS optimization: signaling optimization that        enables the efficient transport of user data (IP, non-IP or SMS)        through a control plane via an MME. This may optionally include        the header compression of IP data.    -   User plane CIoT EPS optimization: signaling optimization that        enables the efficient transport of user data (IP or non-IP)        through a user plane.    -   EPS service(s): a service(s) provided by a PS domain    -   NAS signaling connection: a peer-to-peer S1 mode connection        between a UE and an MME. An NAS signaling connection has a        concatenation of an RRC connection via an LTE-Uu interface and        an S1AP connection via an S1 interface.    -   UE using EPS services with control plane CIoT EPS optimization:        UE attached for EPS services with control plane CIOT EPS        optimization approved by a network    -   Non-access stratum (NAS): a functional layer for exchanging an        UMTS, signaling between a UE and a core network in an EPS        protocol stack, and a traffic message. This has a main function        of supporting the mobility of a UE and supporting a session        management procedure of establishing and maintaining an IP        connection between a UE and a PDN GW.    -   Access stratum (AS): this means a protocol layer under the NAS        layer on the interface protocol between an E-UTRAN (eNB) and a        UE or between an E-UTRAN (eNB) and an MME. For example, in the        control plane protocol stack, the RRC layer, PDCP layer, RLC        layer, MAC layer and PHY layer may be collectively referred to        as an AS layer or any one of the layers may be referred to as an        AS layer. Or, in the user plane protocol stack, the PDCP layer,        RLC layer, MAC layer and PHY layer may be collectively referred        to as an AS layer or any one of the layers may be referred to as        an AS layer.    -   S1 mode: a mode applied to a system having functional separation        according to the use of an S1 interface between a radio access        network and a core network. The S1 mode includes a WB-S1 mode        and an NB-S1 mode.    -   NB-S1 mode: this mode is applied by a UE when a serving radio        access network of the UE provides access to a network service        (via E-UTRA) based on a narrow band (NB)-Internet of things        (IoT).    -   WB-S1 mode: this mode is applied when a system operates in the        S1 mode, but is not the NB-S1 mode.

Limited Service State

In 3GPP TS 23.122, a limited service state (i.e., a no suitable cell) isdefined. According to this part, the following UE operation may beconfirmed.

-   -   The UE in the limited service state does not perform location        registration (LR) except for attach for an emergency bearer        service.    -   In cases of a), c) and f) of the limited service states        described below, the UE may perform Vehicle-to-Everything (V2X)        communication over a PC5 interface.

There is a situation in which a mobile station (MS) may not receive anormal service from a PLMN as described below.

a) Finding a suitable cell of the selected PLMN is unsuccessful;

b) There is no subscriber identity module (SIM) in an MS;

c) When an LR is received, “PLMN not allowed” is responded;

d) When an LR is received, an “illegal MS” or “illegal mobile equipment(ME)” is responded (hereinafter, any SIM in the ME is regarded as“invalid”);

e) When an LR is received, an “IMSI unknown in HLR” is responded(hereinafter, any SIM in the ME is also regarded as “invalid” withrespect to a non-GPRS service);

f) When LR of GPRS MS attached only to a GPRS service is received, “GPRSservices not allowed” is replied (a cell selection state of GPRS MSattached to GPRS and non-GPRS depends on a result of location update) orwhen EPS attach, tracking area update (TAU) or service request isperformed, “EPS services not allowed” is responded; or

g) A power saving mode (PSM) is activated.

In the case of a) to f) described above, the MS attempts to camp on anacceptable cell regardless of a PLMN identifier to make an emergencycall, if necessary. However, an MS that operates in an NB-S1 mode doesnot attempt to make the emergency call. When the MS is in the limitedservice state with a valid SIM, the MS searches for an available andallowable PLMN. Except for the MS other than the eCall only mode, untilvalid SIM exists and a suitable cell may be discovered or passivenetwork reselection is performed, an LR request is not made. In the caseof an MS which is in the eCall only mode, it is excepted that the EPSattach for the emergency bearer service is performed and the LR requestis not made. When the GPRS attach or EPS attach for the emergency bearerservice is performed, the PLMN of a current serving cell is regarded asa PLMN selected during a duration in which the MS is attached for theemergency bearer service. In the limited service state, the presence ofthe MS does not need to be known on which cell of the PLMN the MS camps.

The emergency call may also be made under other conditions. When thelimited service state is caused by a), c), or f), Proximity-basedservices (Prose) direct communication and Prose direct discovery forpublic safety may be initiated if necessary. When the limited servicestate is caused by a), c), or f), the V2X communication over PC5 may beinitiated if necessary.

V2X Communication and Limited Service State

An operation (i.e., V2X communication) in which the UE transmits a V2Xmessage is defined in 3GPP TS 24.386. In this case, the operation of theUE is assumed to be the same as described in ProSe related standard 3GPPTS 24.334 and refers to 3GPP TS 24.334.

An upper layer may request the UE to transmit the V2X message of a V2Xservice identified by a V2X service identifier by using the V2Xcommunication over PC5.

A request from the upper layer includes the following:

a) V2X message;

b) V2X service identifier of the V2X service for the V2X message;

c) Data type (Internet protocol (IP) in V2X message or non-IP);

d) When the V2X message includes non-IP data, an indication for settinga non-IP type field of a non-IP type PDU to a value corresponding to aV2X message family; and

e) V2X message priority

When the UE receives the request from the upper layer to transmit theV2X message of the V2X service identified by the V2X service identifierby using the V2X communication over PC5, the UE performs the followingprocedure:

a) When the following condition is satisfied:

1) The UE is served by E-UTRAN;

2) The UE intends to use a radio resource (i.e., carrier frequency)provided by an E-UTRAN cell;

3) When the UE is served by the E-UTRAN, a registered PLMN belongs to aPLMN list authorized to use the V2X communication over PC5;

4) The V2X service identifier of the V2X service is included in the PLMNlist authorized for the V2X communication over PC5 or the UE isconfigured as a default destination Layer-2 identifier (ID) for the V2Xcommunication over PC5;

In this case, the UE operates as follows:

1) Requesting the radio resource for the V2 communication over PC5; and

2) performing transmission of the V2X communication over PC5

b) On the contrary, when the following conditions are satisfied:

1) The UE:

A) is “not served by E-UTRAN”; or

B) is in the EMM-IDLE mode and the limited service state, a case wherethe UE is in the limited service state corresponds to any one of thefollowings cases;

i) a case where the UE may not find the suitable cell in the selectedPLMN;

ii) a case where the UE receives an ATTACH REJECT message, a TRACKINGAREA UPDATE REJECT message, or a SERVICE REJECT message including EMMcause #11 “PLMN not allowed” or the UE receives a LOCATION UPDATINGREJECT message, a GPRS ATTACH REJECT message, or a ROUTING AREA UPDATEREJECT message including EMM cause #11 “PLMN not allowed”; or

iii) a case where the UE receives the ATTACH REJECT message or TRACKINGAREA UPDATE REJECT message or SERVICE REJECT message including EMM cause#7 “EPS services not allowed” or a case where the UE receives theLOCATION UPDATING REJECT message or GPRS ATTACH REJECT message orROUTING AREA UPDATE REJECT message or SERVICE REJECT message includingEMM cause #7 “EPS services not allowed”;

2) When the UE is not served by the E-UTRAN, the UE is authorized to usethe V2X communication over PC5; and

3) The V2X service identifier of the V2X service is included in a listof the V2X services authorized for the V2X communication over PC5 or theUE is configured as a default destination Layer-2 identifier (ID) forthe V2X communication over PC5;

In this case, the UE operates as follows:

1) selecting the radio resource for the V2 communication over PC5; and

2) performing the transmission of the V2X communication over PC5;

Otherwise, the UE does not perform the V2X communication over PC5.

V2X Communication and PC5 Resource Management/Allocation

According to 3GPP TS 23.285, when the attach, the service request, orthe TAU procedure is performed, the MME transfers a UE context to theeNB as an S1-AP Initial UE Context Setup Request message, the eNB storesthe information and uses the stored information for managing a PC5resource of the UE.

1) E-UTRAN Attach Procedure

An E-UTRAN attach procedure for a V2X-enabled UE is performed as definedin 3GPP TS 23.401 with the following additions:

-   -   The UE encapsulates the V2X capability indication as a part of        the “UE network capability” in the Attach Request message. The        MME stores the information for the V2X operation. A V2X        capability indicates whether the UE may support the V2X        communication over PC5 reference point.    -   When the UE indicates the V2X capability, the UE is authorized        for the V2X communication via the PC5 reference point based on        subscription data. In addition, the MME encapsulates an        indication “V2X services authorized” indicating that the UE is        authorized to use the V2X communication over PC5 reference point        in the S1-AP Initial Context Setup Request.    -   The MME acquires Aggregate Maximum Bit Rate (UE-PC5-AMBR) from        HSS as a part of the subscriber data and encapsulates the        UE-PC5-AMBR in the S1-AP Initial Context Setup Request and        transmits the UE-PC5-AMBR to the eNB. The eNB uses the        UE-PCS-AMBR for resource management of PC5 transmission of the        UE for the V2X service in a network scheduled mode.

2) Service Request Procedures

The Service Request procedures for the UE are performed as defined in3GPP TS 23.401 with the following additions:

-   -   When the UE is V2X-enabled and authorized to use the V2X        communication over PC5 reference point based on the subscriber        data, the MME includes the indication “V2X services authorized”        indicating that the UE is authorized to use the V2X        communication over PC5 reference point in the S1-AP Initial        Context Setup Request.    -   The MME encapsulates the UE-PC5-AMBR in the S1-AP Initial        Context Setup Request and transmits the UE-PC5-AMBR to the eNB.        The eNB stores the UE-PC5-AMBR as a part of the UE context and        uses the UE-PC5-AMBR for resource management of PC5 transmission        of the UE for the V2X service in the network scheduled mode.

3) S1 Handover Procedures

An intra-E-UTRAN S1-based handover for UE or an inter-RAT handoverprocedure to E-UTRAN is performed as defined in 3GPP TS 23.401, and thefollowing is added:

-   -   When the UE is V2X-enabled and the UE is authorized to use the        V2X communication over PC5 reference point based on the        subscriber data, a target MME transmits to the target eNB the        “V2X services authorized” indication and the UE-PC5-AMBR as        follows:    -   In the case of the intra MME handover, the “V2X services        authorized” indication and the UE-PC5-AMBR are included in an        S1-AP Handover Request message. When the “V2X services        authorized” indication or the UE-PC5-AMBR or both are changed        after the handover procedure, an updated “V2X services        authorized” indication or the updated PC5-AMBR or both are        included in the S1-AP UE Context Modification Request message        and transmitted to a target eNB.    -   In the case of inter MME handover or inter-RAT handover to the        E-UTRAN, after the handover procedure, the “V2X services        authorized” indication and the UE-PC5-AMBR are included in the        S1-AP UE Context Modification Request message and transmitted to        the target eNB.

4) X2 Handover Procedures

In the case of X2-based handover, the “V2X services authorized”indication and UE-PC5-AMBR are transmitted to the target eNB as follows:

-   -   When a source eNB is V2X-enabled and the “V2X services        authorized” indication is included in the UE context, the source        eNB encapsulates the “V2X services authorized” indication and        the UE-PC5-AMBR in an X2-AP handover request message and        transmits the “V2X services authorized” indication and the        UE-PC5-AMBR to the target eNB.    -   When the UE is V2X-enabled and the UE is authorized to use the        V2X communication via the PC5 reference point based on the        subscription data, the MME encapsulates the “V2X services        authorized” indication and the UE-PC5-AMBR in a Path Switch        Request Acknowledge message and transmits the “V2X services        authorized” indication and the UE-PC5-AMBR to the target eNB.        When the “V2X services authorized” indication or the UE-PC5-AMBR        or both are changed after the handover procedure, an updated        “V2X services authorized” indication or the updated PC5-AMBR or        both are included in the S1-AP UE Context Modification Request        message and transmitted to a target eNB.

The “V2X services authorized” indication transmitted to the target eNBindicates that the UE is authorized to use the V2X communication overPC5.

The UE-PC5-AMBR is transmitted to the target eNB for the resourcemanagement of the PC5 transmission of the UE in the V2X communication.

5) Tracking Area Update (TAU) Procedure

The TAU procedure for the UE is performed as defined in 3GPP TS 23.401and the following is added:

-   -   The UE encapsulates the V2X capability indication as a part of        the “UE network capability” in the Tracking Area Update Request        message. The MME stores the information for the V2X operation.    -   When the MME may determine to re-establish radio and S1 bearers        for all activated EPS bearer contexts due to an “active” flag or        pending downlink data or signaling included in the Tracking Area        Update Request message, the UE is V2X-enabled, and the UE is        authorized to use the V2X communication over PC5 reference point        based on the subscriber data, the MME encapsulates the “V2X        services authorized” indication and the UE-PC5-AMBR in the S1-AP        Initial Context Setup Request message.

6) Insert Subscriber Data procedure

The Insert Subscriber Data procedure for the UE is performed as definedin 3GPP TS 23.401 and the following is added:

When the “V2X services authorized” indication or the UE-PC5-AMBR or bothneed to be changed due to the changed subscription data and the S1bearer is established, the MME notifies an updated “V2X servicesauthorized” indication or the updated PC5-AMBR or both to a target eNBvia the S1-AP UE Context Modification Request message.

7) Delete Subscriber Data Procedure

The Delete Subscriber Data procedure for the UE is performed as definedin 3GPP TS 29.272 with the same additions described as 6) above.

V2X Communication and PC5 Resource Management/Allocation

As described above, in the case where ‘the UE is served by E-UTRAN’, theradio resource of the V2X communication via the PC5 is described withreference to section 10.2.2 of 3GPP TS 24.334.

According to contents to be described below, when the UE is served bythe E-UTRAN (e.g., in coverage of the E-UTRAN) and intends to use a V2X(ProSe) radio resource provided by the E-UTRAN (e.g., eNB), the UErequests to a lower layer (i.e., AS layer) parameters required fortransmission/reception of the V2X communication (ProSe directcommunication).

Specifically, when the eNB provides a corresponding radio resource pool(i.e., in the case of mode 4), the UE may perform the V2X communicationby using the radio resource of the corresponding pool in the EMM-IDLEstate.

When V2X related information is transmitted to broadcast information,but a resource pool for transmission is not broadcasted (i.e., only whenthe V2X message transmission is performed through a dedicated resourcefor the UE by establishing the RRC connection) (i.e., mode 3), the UEneeds to request the radio resource to the eNB. Further, in this case,when the UE is in the EMM-IDLE, the UE needs to be switched toEMM-CONNECTED in order to request the radio resource to the eNB. To thisend, the service request procedure or the TAU request needs to beperformed. Contents thereof are defined in section 10.2.2 of 3GPP TS24.334 as described below.

When the UE is served by the E-UTRAN and the UE intends to use the ProSeradio resource (i.e., carrier frequency) provided by an E-UTRAN cell,the UE requests the parameters to the lower layer in order to transmitor receive the ProSe direct communication. Only when the lower layerindicates that the ProSe direct communication is supported by thenetwork, the UE performs direct communication. When the UE in theEMM-IDLE mode needs to request the resource for the ProSe directcommunication, the UE needs to perform the service request procedure orthe TAU procedure. When the radio resource for transmitting or receivingthe ProSe direct communication is provided by the eNB, the UE starts theProSe direct communication.

V2X Communication and PC5 Resource Management/Allocation (Sidelink UEInformation)

In 3GPP TS 36.331, contents regarding sidelink UE informationtransmitted by the UE are described. The sidelink UE information ismainly used to announce an interest (i.e., desiring the V2Xcommunication) in sidelink communication of the UE to be allocated withthe PC 5 radio resource from the eNB.

FIG. 7 is a diagram illustrating a sidelink UE information procedure ina wireless communication system to which the present invention may beapplied.

The purpose of the Sidelink UE information procedure is to allow the UEto request the allocation or release of transmission resources forsidelink communication or discovery reception, V2X sidelinkcommunication reception, or sidelink communication or discoveryannouncement, or to announce to the E-UTRAN that the UE is interested inreporting sidelink discovery-related parameters from the systeminformation of the inter-frequency/PLMN cell or is no longer interested.

When the interest is changed at the time of establishing a successfulconnection, a UE which is in RRC_CONNECTED, which is capable ofperforming sidelink communication, V2X sidelink communication, orsidelink discovery may initiate a procedure for indicating that there isan interest in receiving the sidelink communication, V2X sidelinkcommunication, or sidelink discovery, when a primary cell (PCell) ischanged, which broadcasts system information block (SIB) type 18(‘SystemInformationBlockType18’), SystemInformationBlockType19, orSystemInformationBlockType21 including a sidelink V2X commonconfiguration (‘sl-V2X-ConfigCommon’) parameter.

The UE capable of performing the sidelink communication, V2X sidelinkcommunication, or sidelink discovery may initiate a procedure forrequesting allocation of dedicated resources for related sidelinkcommunication transmission, discovery announcement, or V2X sidelinkcommunication transmission or requesting a sidelink discovery gap fortransmitting or receiving the sidelink discovery. In addition, a UEcapable of reporting an inter-frequency/PLMN sidelink discoveryparameter may initiate a procedure for reporting parameters related tothe sidelink discovery from system information of aninter-frequency/PLMN cell.

When the procedure is initiated, the UE:

1> when SystemInformationBlockType18 is broadcasted by the PCell:

2> ensures to have a valid version of SystemInformationBlockType18 forthe PCell;

2> when the sidelink communication is configured to be received by theupper layer:

3> when the UE last enters an RRC_CONNECTED state and then, the UE doesnot transmit sidelink UE information (SidelinkUEInformation) message; or

3> when the UE is connected to PCell which does not broadcastSystemInformationBlockType18 from a last time when the UE transmits theSidelinkUEInformation message; or

3> when last transmission of SidelinkUEInformation does not include acommon reception interest frequency (‘commRxInterestedFreq’) parameteror when a frequency configured by the upper layer is changed to receivethe sidelink communication after the last transmission of theSidelinkUEInformation message:

4> the UE initiates transmission of the SidelinkUEInformation message inorder to indicate an interested sidelink communication receptionfrequency.

2> Otherwise:

3> when the last transmission of the SidelinkUEInformation messageincludes a commRxInterestedFreq parameter:

4> the UE initiates transmission of the SidelinkUEInformation message inorder to indicate that there is no interest in receiving the sidelinkcommunication any longer.

2> when one-to-many sidelink communication not related to a relay isconfigured by the upper layer:

3> when the UE last enters the RRC_CONNECTED state and then, does nottransmit the SidelinkUEInformation message; or

3> when the UE is connected to the PCell which does not broadcastSystemInformationBlockType18 from the last time when the UE transmitsthe SidelinkUEInformation message; or

3> when the last transmission of SidelinkUEInformation does not includea common transmission resource frequency (‘commTxResourceReq’) parameteror when information delivered by the commTxResourceReq is changed afterthe last transmission of the SidelinkUEInformation message:

4> the UE initiates transmission of the SidelinkUEInformation message inorder to indicate a one-to-many sidelink communication resource notrelated to the relay requested by the UE;

2> Otherwise:

3> when transmission of the SidelinkUEInformation message includes thecommTxResourceReq:

4> the UE initiates transmission of the SidelinkUEInformation message inorder to indicate not to request the one-to-many sidelink communicationtransmission resource not related to the relay;

2> when the one-to-many sidelink communication related to the relay isconfigured to be transmitted by the upper layer:

3> when the UE enters the RRC_CONNECTED state and then, does nottransmit the SidelinkUEInformation message; or

3> when the UE is connected to PCell that does not broadcastSystemInformationBlockType18, PCell that does not broadcastSystemInformationBlockType19, or PCell that broadcastSystemInformationBlockType19 not including a relay discoveryconfiguration (‘discConfigRelay’) from the last time when the UEtransmits the SidelinkUEInformation message; or

3> when the last transmission of the SidelinkUEInformation message doesnot include the common transmission resource frequency(‘commTxResourceReq’) parameter or when the information delivered by thecommTxResourceReq is changed after the last transmission of theSidelinkUEInformation message:

One-to-Many Prose Direct Communication Transmission not Served byE-UTRAN

As described above, when the UE is not served by the E-UTRAN, a processof selecting the radio resource for the V2X communication over PC5 is asfollows.

When the UE is not served by the E-UTRAN, an operation order is asfollows.

1) The UE finds radio parameters mapped to a geographical area based ona configuration parameter.

2) The UE checks whether there is interference in the correspondingradio parameter.

3) When there is no interference, the V2X communication over PC5 isperformed by using the corresponding radio parameter.

On the contrary, when there is the interference, the PLMN of thecorresponding cell is checked and when the PLMN is a registered PLMN ora PLMN equivalent to the registered PLMN and included in an authorizedPLMN list, the V2X communication over PC5 is performed by moving acorresponding cell (without a PLMN selecting operation).

In other cases, when the following conditions are satisfied, the ProSedirect communication is performed.

A. When the PLMN reported by the lower layer is not the registered PLMNor the PLMN equivalent to the registered PLMN; and

B. At least one of the PLMNs reported by the lower layer is included inthe authorized PLMN list for the ProSe direct communication and providesthe radio resource for the ProSe direct communication;

Procedure of Using Provisioned Radio Resources by UE

When the UE is not served by the E-UTRAN, the UE selects radioparameters to be used for the ProSe direct communication as follows.

-   -   When the UE may autonomously determine that the UE is positioned        in a geographical area and when the radio parameters for the        geographical area are provisioned to the UE, the UE selects the        radio parameters associated with the geographical area; or    -   In all other cases, the UE does not initiate the ProSe direct        communication.

Before initiating the ProSe direct communication, the UE checks whetherthe radio parameter selected by the lower layer may be used at a currentlocation without interference.

-   -   When the lower layer indicates that the usage does not cause the        interference, the UE initiates the ProSe direct communication;        or    -   Otherwise, when the lower layer reports one or more PLMNs in the        provisioned radio resource (i.e., carrier frequency),

a) When the following conditions are satisfied:

1) when the PLMN reported by the lower layer is not the registered PLMNor the PLMN equivalent to the registered PLMN; and

2) at least one of the PLMNs reported by the lower layer is included inthe authorized PLMN list for the ProSe direct communication and providesthe radio resource for the ProSe direct communication.

In this case, the UE operates as follows:

1) in the EMM-IDLE mode, the UE performs PLMN selection triggered by theProSe direct communication; or

2) otherwise, when the UE is in the EMM-CONNECTED mode:

i) the UE performs a detach procedure and performs the PLMN selectiontriggered by the ProSe direct communication; or

ii) the UE does not initiate the ProSe direct communication.

The UE follows implementation of the UE with respect to whether toperform any operation of i) or ii) above.

b) Otherwise, the UE does not initiate the ProSe direct communication.

When the registration in the selected PLMN is successful, the UEperforms the procedure for initiating the ProSe direct communication.

When the UE deviates from the geographical area while performing theProSe direct communication by using the radio parameter associated withthe geographical area, the UE stops performing the ProSe directcommunication.

-   -   When the UE is not served by the E-UTRAN or when the UE intends        to use the radio resources for the ProSe other than radio        resources operated by the serving E-UTRAN cell, the UE selects        appropriate radio parameters for a new geographical area; or    -   when the UE is served by the E-UTRAN and intends to use the        radio resources for the ProSe operated by the serving E-UTRAN        cell, the UE performs the procedure for initiating the ProSe        direct communication when being served by the E-UTRAN.

Sidelink Pre-Configured Parameters

The following shows contents for configured radio parameters for the UE.SL-Preconfiguration shows configured radio parameters for Rel-12 orRel-13 ProSe (D2D) and SL-V2X-Preconfiguration shows a configured radioparameter for the V2X communication over PC5 of Rel-14. According to ahighlighted part below, in the case of SL-V2X-Preconfiguration, one ormore frequencies (carriers) may be configured unlikeSL-Preconfiguration.

1) Specified Parameter

Table 2 below shows parameters of which values are specified in thestandard.

TABLE 2 Name Value Semantics description VersionpreconfigSync >syncTxParameters >>alpha 0preconfigComm >sc-TxParameters >>alpha 0 >dataTxParameters >>alpha 0

2) Pre-Configurable Parameter

Table 3 shows Abstract Syntax Notation.1 (ASN.1) indicating a start ofE-UTRA definition of pre-configured sidelink parameters.

TABLE 3 -- ASN1START EUTRA-Sidelink-Preconf DEFINITIONS AUTOMATIC TAGS::= BEGIN IMPORTS AdditionalSpectrumEmission, ARFCN-ValueEUTRA-r9,FilterCoefficient, maxFreq, maxSL-TxPool-r12,maxSL-CommRxPoolPreconf-v1310, maxSL-CommTxPoolPreconf-v1310,maxSL-DiscRxPoolPreconf-r13, maxSL-DiscTxPoolPreconf-r13,maxSL-V2X-RxPoolPreconf-r14, maxSL-V2X-TxPoolPreconf-rl4, P-Max,ReselectionInfoRelay-r13, SL-CommTxPoolSensingConfig-r14, SL-CP-Len-r12,SL-HoppingConfigComm-r12, SL-OffsetIndicator-r12,SL-OffsetIndicatorSync-r12, SL-PeriodComm-r12, RSRP-RangeSL3-r12,SL-PriorityList-r13, SL-TF-ResourceConfig-r12, SL-TRPT-Subset-r12,SL-TxParameters-r12, SL-ZoneConfig-r14, P0-SL-r12, TDD-ConfigSL-r12,SubfameBitmapSL-r14 FROM EUTRA-RRC-Definitions; -- ASN1STOP

-   -   SL-Preconfiguration

An SL-Preconfiguration information element (IE) includes the sidelinkpre-configured parameter.

Table 4 shows the SL-Preconfiguration IE.

TABLE 4 -- ASN1START SL-Preconfiguration-r12 ::= SEQUENCE {preconfigGeneral-r12 SL-PreconfigGeneral-r12, preconfigSync-r12SL-PreconfigSync-r12, preconfigComm-r12 SL- PreconfigCommPoolList4-r12,..., [[ preconfigComm-v1310 SEQUENCE { commRxPoolList-r13 SL-PreconfigCommRxPoolList-r13, commTxPoolList-r13 SL-PreconfigCommTxPoolList-r13 OPTIONAL } OPTIONAL, preconfigDisc-r13SEQUENCE { discRxPoolList-r13 SL- PreconfigDiscRxPoolList-r13,discTxPoolList-r13 SL- PreconfigDiscTxPoolList-r13 OPTIONAL } OPTIONAL,preconfigRelay-r13 SL-PreconfigRelay-r13 OPTIONAL ]] }SL-PreconfigGeneral-r12 ::= SEQUENCE { -- PDCP configurationrohc-Profiles-r12 SEQUENCE { profile0x0001-r12 BOOLEAN,profile0x0002-r12 BOOLEAN, profile0x0004-r12 BOOLEAN, profile0x0006-r12BOOLEAN, profile0x0101-r12 BOOLEAN, profile0x0102-r12 BOOLEAN,profile0x0104-r12 BOOLEAN }, -- Physical configuration carrierFreq-r12ARFCN-ValueEUTRA-r9, maxTxPower-r12 P-Max,additionalSpectrumEmission-r12 AdditionalSpectrumEmission,sl-bandwidth-r12 ENUMERATED {n6, n15, n25, n50, n75, n100},tdd-ConfigSL-r12 TDD-ConfigSL-r12, reserved-r12 BIT STRING (SIZE (19)),... } SL-PreconfigSync-r12 ::= SEQUENCE { syncCP-Len-r12 SL-CP-Len-r12,syncOffsetIndicator1-r12 SL-OffsetIndicatorSync-r12,syncOffsetIndicator2-r12 SL-OffsetIndicatorSync-r12,syncTxParameters-r12 P0-SL-r12, syncTxThreshOoC-r12 RSRP-RangeSL3-r12,filterCoefficient-r12 FilterCoefficient, syncRefMinHyst-r12 ENUMERATED{dB0, dB3, dB6, dB9, dB12}, syncRefDiffHyst-r12 ENUMERATED {dB0, dB3,dB6, dB9, dB12, dBinf}, ..., [[ syncTxPeriodic-r13 ENUMERATED {true}OPTIONAL ]] } SL-PreconfigCommPoolList4-r12 ::= SEQUENCE (SIZE(1..maxSL-TxPool-r12)) OF SL- PreconfigCommPool-r12SL-PreconfigCommRxPoolList-r13 ::= SEQUENCE (SIZE (1..maxSL-CommRxPoolPreconf-v1310)) OF SL-PreconfigCommPool-r12SL-PreconfigCommTxPoolList-r13 ::= SEQUENCE (SIZE (1..maxSL-CommTxPoolPreconf-v1310)) OF SL-PreconfigCommPool-r12SL-PreconfigCommPool-r12 ::= SEQUENCE { -- This IE is same asSL-CommResourcePool with rxParametersNCell absent sc-CP-Len-r12SL-CP-Len-r12, sc-Period-r12 SL-PeriodComm-r12, sc-TF-ResourceConfig-r12SL-TF-ResourceConfig-r12, sc-TxParameters-r12 P0-SL-r12, data-CP-Len-r12SL-CP-Len-r12, data-TF-ResourceConfig-r12 SL-TF-ResourceConfig-r12,dataHoppingConfig-r12 SL-HoppingConfigComm-r12, dataTxParameters-r12P0-SL-r12, trpt-Subset-r12 SL-TRPT-Subset-r12, ..., [[ priorityList-r13SL-PriorityList-r13 OPTIONAL -- For Tx ]] }SL-PreconfigDiscRxPoolList-r13 ::= SEQUENCE (SIZE(1..maxSL-DiscRxPoolPreconf- r13)) OF SL-PreconfigDiscPool-r13SL-PreconfigDiscTxPoolList-r13 ::= SEQUENCE (SIZE(1..maxSL-DiscTxPoolPreconf- r13)) OF SL-PreconfigDiscPool-r13SL-PreconfigDiscPool-r13 ::= SEQUENCE { -- This IE is same asSL-DiscResourcePool with rxParameters absent cp-Len-r13 SL-CP-Len-r12,discPeriod-r13 ENUMERATED {rf4, rf6, rf7, rf8, rf12, rf14, rf16, rf24,rf28, rf32, rf64, rf128, rf256, rf512, rf1024, spare}, numRetx-r13INTEGER (0..3), numRepetition-r13 INTEGER (1..50), tf-ResourceConfig-r13SL-TF-ResourceConfig-r12, txParameters-r13 SEQUENCE {txParametersGeneral-r13 P0-SL-r12, txProbability-r13 ENUMERATED {p25,p50, p75, p100} } OPTIONAL, ... } SL-PreconfigRelay-r13 ::= SEQUENCE {reselectionInfoOoC-r13 ReselectionInfoRelay-r13 } -- ASN1STOP

Table 5 shows description of SL-Preconfiguration fields.

TABLE 5 Description of SL-Preconfiguration fields carrierFreq This fieldindicates the carrier frequency when the UE is out of the sidelinkcommunication and sidelink discovery coverage. Frequency division duplex(FDD) may correspond to an uplink carrier frequency and thecorresponding downlink frequency may be determined from default TX-RXfrequency separation. commRxPoolList This field indicates a list ofreceiving pools for the sidelink communication in addition to a resourcepool indicated by ‘preconfigComm’. commTxPoolList This field indicates alist of the transmitting pools for the sidelink communication inaddition to the resource pool indicated by ‘preconfigComm’.preconfigComm This field indicates the list of the resource pools. Afirst resource pool in the list is used for both reception andtransmission of the sidelink communication. When other resource poolsare present, the corresponding resource pool is used only for thereception of the sidelink communication. syncRefDiffHyst This field ishysteresis when evaluating a synchronization reference (SyncRef) UE byusing a relative comparison. The value dB 0 corresponds to 0 dB, thevalue dB 3 corresponds to 3 dB, and other values are also similar. Avalue dBinf corresponds to infinite dB. syncRefMinHyst This field ishysteresis when evaluating a synchronization reference (SyncRef) UE byusing an absolute comparison. The value dB 0 corresponds to 0 dB, thevalue dB 3 corresponds to 3 dB, and other values are also similar.

-   -   sidelink SL-V2X-Preconfiguration

The SL-V2X-Preconfiguration IE includes the sidelink pre-configuredparameters used for the V2X sidelink communication.

Table 6 shows the V2X-Preconfiguration IE.

TABLE 6 -- ASN1START SL-V2X-Preconfiguration-r14 ::= SEQUENCE (SIZE(1..maxFreq)) OF SL-V2X- PreconfigFreqInfo-r14SL-V2X-PreconfigFreqInfo-r14 ::= SEQUENCE { v2x-CommPreconfigGeneral-r14SL-PreconfigGeneral-r12, v2x-CommPreconfigSync-r14 SL-PreconfigSync-r12,v2x-CommRxPoolList-r14 SL-PreconfigV2X- RxPoolList-r14,v2x-CommTxPoolList-r14 SL-PreconfigV2X- TxPoolList-r14,v2x-ResourceSelectionConfig-r14 SL- CommTxPoolSensingConfig-r14OPTIONAL, zoneConfig-r14 SL-ZoneConfig-r14 OPTIONAL, ... }SL-PreconfigV2X-RxPoolList-r14 ::= SEQUENCE (SIZE (1..maxSL-V2X-RxPoolPreconf-r14)) OF SL-V2X-PreconfigCommPool-r14SL-PreconfigV2X-TxPoolList-r14 ::= SEQUENCE (SIZE (1..maxSL-V2X-TxPoolPreconf-r14)) OF SL-V2X-PreconfigCommPool-r14SL-V2X-PreconfigCommPool-r14 ::= SEQUENCE { -- This IE is same asSL-V2X-CommResourcePool with rxParametersNCell absentsl-OffsetIndicator-r14 SL-OffsetIndicator-r12 OPTIONAL, sl-Subframe-r14SubframeBitmapSL-r14, adjacencyPSCCH-PSSCH-r14 BOOLEAN,sizeSubchannel-r14 ENUMERATED { n4, n5, n6, n8, n9, n10, n12, n15, n16,n18, n20, n25, n30, n48, n50, n72, n75, n96, n100, spare13, spare12,spare11, spare 10, spare9, spare8, spare7, spare6, spare5, spare4,spare3, spare2, spare1}, numSubchannel-r14 ENUMERATED {n1, n3, n5, n10,nl5, n20, spare2, spare1}, startRB-Subchannel-r14 INTEGER (0..99),startRB-PSCCH-Pool-r14 INTEGER (0..99) OPTIONAL, dataTxParameters-r14SL-TxParameters-r12 OPTIONAL, zoneID-r14 INTEGER (0..7) OPTIONAL, ... }END -- ASN1ST0P

Table 7 shows the description of the SL-V2X-Preconfiguration fields.

TABLE 7 Description of SL-V2X-Preconfiguration fieldsadjacencyPSCCH-PSSCH This field indicates whether a physical sidelinkcontrol channel (PSCCH) and a physical sidelink shared channel (PSSCH)are continuously transmitted (indicated as TRUE) in an adjacent resourceblock (RB) or whether the PSCCH and the PSSCH are transmitted in an non-adjacent RB (indicated as FALSE). This parameter is shown only when thepool is configured so that the UE transmits the PSCCH and the PSSCHassociated therewith in the same subframe. numSubchannel This fieldindicates the number of subchannels in the corresponding resource pool.sizeSubchannel This field indicates the number of physical resourceblocks (PRBs) of each subchannel in the corresponding resource pool.sl-OffsetIndicator This field indicates an offset of a first subframe ofthe resource pool within a system frame number (SFN) cycle. Otherwise,the resource pool starts from the first subframe of a frame with SFN =0. sl-Subframe This field indicates a bitmap of the resource pool. Thebitmap is repeated within the SFN cycle. startRB-Subchannel This fieldindicates a lowest RB index of a subchannel having a lowest index.startRB-PSCCH-Pool This field indicates a lowest RB index of a PSCCHpool. v2x-CommRxPoolList This field indicates a list of reception poolsfor the V2X sidelink communication. v2x-CommTxPoolList This fieldindicates a list of transmission pools for the V2X sidelinkcommunication. v2x-ResourceSelectionConfig This field indicates a V2Xsidelink communication configuration used for an autonomous resourceselection of the UE. zoneConfig This field indicates a zoneconfiguration for the V2X sidelink communication. zoneID This fieldindicates a zone ID for the UE to use the corresponding resource pool.

Attach Procedure

The UE/user needs to be registered in the network in order to receive aservice for requesting registration. The registration is referred to asnetwork attachment. Always-on Internet protocol (IP) connectivity forthe UE/user of the EPS may be enabled by establishing a default EPSbearer during the network attachment. A policy and charging control(PCC) rule applied to the default EPS bearer may be pre-defined in P-GWand activated during attachment by the P-GW. In the attach procedure,one or multiple dedicated bearer establishment procedures may betriggered in order to establish a dedicated EPS bearer(s) for the UE andthe UE may request IP address allocation.

During an initial attach procedure, a mobile equipment (ME) identity isobtained from the UE. An MME operator may check the ME identity by anequipment identity register (EIR). The MME delivers the ME identity tothe HSS and the P-GW.

The E-UTRAN Initial Attach procedure needs to perform the emergencyservice, but is used for Emergency Attach by the UE which may notacquire a general service from the network. The UE is in the limitedservice state. Further, the UE is attached to the general service doesnot have the established emergency bearer and camps on the cell (e.g., alimited tracking area or not allowed Closed Subscriber Group (CSG)) inthe limited service state also initiates the attach procedure whileindicating that the corresponding attach is for receiving the emergencyservice. In general, when the UE (i.e., the UE which is not in thelimited service state) which camps on the cell is not already attached,the UE should initiate general initial attach and should initiate a UERequested PDN Connectivity procedure in order to receive the emergencyEPS bearer service.

In order to restrict the load on the network, when E-UTRAN attach isperformed by new PLMN (i.e., not registered PMN or not PLMN equivalentto the registered PLMN), the UE configured to perform attach by IMSIshould identify itself instead of a stored temporary identifier at thetime of changing the PLMN.

This procedure is also used for establish first PDN connection throughthe E-UTRAN when the UE already has a PDN connection activated via thenon-3GPP access network and wishes to establish a PDN connectionsimultaneously with different access point names (APNs) through multipleaccesses.

FIG. 8 is a diagram schematically exemplifying an attach procedure in awireless communication system to which the present invention may beapplied.

The Attach procedure is generally used for establishing connection withthe network when the UE enters the E-UTRAN cell. Further, the Attachprocedure may be used even when the non-3GPP network is handed over tothe E-UTRAN.

1-2. The UE initiates the attach procedure by transmitting the attachrequest message to the MME.

The Attach Request message includes an International Mobile SubscriberIdentity (IMSI) of the UE, a PDN type requested by the UE, and the like.Here, the PDN type indicates an IP version (i.e., IPv4, IPv4v6, IPv6)requested by the UE.

The Attach Request message is forwarded while being included in the RRCConnection Setup Complete message in the RRC connection and forwardedwhile being included in the Initial UE message in the S1 signalingconnection.

The UE may transmit the Attach Request message together with the PDNConnectivity Request message in order to request the PDN connectivity.

3. The MME requests information for authentication to the HSS andreceives the requested information for UE authentication and performsmutual authentication with the UE.

4. The MME registers the location of the UE in the HSS and receives usersubscription information (i.e., subscribed QoS Profile) from the HSS inorder to generate a default bearer to the UE.

Here, in the case of dynamic IP address allocation, the subscriptioninformation does not include IP address information for thecorresponding UE, but in the case of static IP address allocation, thesubscription information includes static IP address informationallocated to the corresponding UE.

5. The MME allocates a default EPS bearer ID and transmits a CreateSession Request message to the S-GW.

The Create Session Request message includes the IMSI of the UE, the EPSbearer ID, a P-GW ID (i.e., P-GW address which the MME selects forcreating the EPS bearer, a subscription QoS profile, a PDN type, an IPaddress (i.e., PDN address) of the UE, and the like.

Here, the PDN type similarly includes PDN type information received fromthe UE. In the case of the dynamic IP address allocation, the IP addressof the UE may be set to 0 and in the case of the static IP addressallocation, the IP address of the UE may be set to allocated static IPaddress information (included in the subscription information).

6. The S-GW allocates an S5 S-GW Tunnel Endpoint Identifier (TEID) tothe corresponding P-GW included in the Create Session Request messagereceived from the MME in order to generate a S5 bearer to the P-GW andtransmits the Create Session Request message to the corresponding P-GW.

The Create Session Request message includes the IMSI of the UE, the EPSbearer ID, the S5 S-GW TEID, the APN, the subscription QoS profile, aPDN type (i.e., IP version), an IP address (i.e., PDN address) of theUE, and the like.

7. The P-GW allocates an Internet Protocol (IP) address to be used bythe UE and performs an IP connectivity access network (IP-CAN) sessionestablishment/modification procedure with the PCRF.

In this case, in the case of the dynamic IP address allocation, the IPaddress selected in the IP address pool possessed by the P-GW may beallocated to the UE and in the case of the static IP address allocation,static IP address information (included in the subscription information)allocated to the corresponding UE may be similarly allocated.

8. The P-GW allocates a P-GW Tunnel Endpoint Identifier (TEID) to theS-GW to create the S5 bearer and transmits a Create Session Response tothe S-GW in response to the Create Session Request message.

The Create Session Response message includes the IMSI of the UE, the EPSbearer ID, the S5 S-GW TEID, the subscription QoS profile, the PDN type,the IP address (i.e., PDN address) allocated to the UE, and the like.

When the P-GW selects the PDN type different from the requested PDNtype, the P-GW indicates to the UE a cause indicating why the PDN typeis modified together with the PDN type.

When such a procedure is completed, creation of the S5 bearer betweenthe S-GW and the P-GW is completed, and as a result, the S-GW maytransmit uplink traffic to the P-GW or receive downlink traffic from theP-GW.

9. The S-GW allocates an S1 S-GW TEID P-GW to create the S1 bearer andtransmits the Create Session Response to the MME in response to theCreate Session Request message.

The Create Session Response message includes the IMSI of the UE, the EPSbearer ID, the S1 S-GW TEID, the PDN type, the IP address (i.e., PDNaddress) allocated to the UE, and the like.

10-11. The MME transmits an Attach Accept message to the UE in responseto an Attach Accept message.

The Attach Accept message includes an EPS bearer ID, an APN, an IPaddress (i.e., a PDN address) of the UE allocated by the P-GW, a PDNtype, a Tracking Area Identity (TAI) list, a TAU timer, and the like.

The Attach Accept message is included in an Initial Context SetupRequest message and forwarded to the eNB in the S1 signalingconnectivity.

When such a procedure is completed, creation of an uplink S1 bearerbetween the eNB and the S-GW may be completed and the eNB may transmitthe uplink traffic to the S-GW.

In addition, the Attach Accept message is included in an RRC ConnectionReconfiguration message and forwarded from the eNB to the UE in the RRCconnectivity.

When such a procedure is completed, creation of DRB between the UE andthe eNB is completed, and as a result, the UE may transmit the uplinktraffic to the eNB or receive the downlink traffic from the eNB.

12. The eNB transmits an Initial Context Setup Response message to theMME in response to an Initial Context Setup Request message. The InitialContext Setup Response message includes an S1 eNB TEID and the like.

13-14. The UE transmits an Attach Complete message to the MME inresponse to the Attach Accept message.

The Attach Complete message is transferred while being included in a ULInformation Transfer message in the RRC connectivity and transferred inan Uplink NAS Transport message in the S1 signaling connectivity.

When such a procedure is completed, creation of the default EPS bearerbetween the UE and the P-GW is completed, and as a result, the UE maytransmit uplink data to the P-GW.

15. The MME transfers the S1 eNB TEID received from the eNB to the S-GWthrough a Modify Bearer Request message.

When such a procedure is completed, creation of a downlink S1 bearerbetween the eNB and the S-GW may be completed and the eNB may receivethe downlink traffic from the S-GW.

16-17. As necessary, the bearer is updated between the S-GW and theP-GW.

18. The S-GW transmits a Modify Bearer Response message to the MME inresponse to the Modify Bearer Request message.

When such a procedure is completed, creation of the default EPS bearerbetween the UE and the P-GW is completed, and as a result, the P-GW maytransmit downlink data to the UE. That is, the UE may establish theconnection with the PDN and receive a PDN service by using the allocatedIP address.

19. The MME sends a Notify Request message including the P-GW ID (i.e.,P-GW address) and APN to the HSS as needed.

20. The HSS transmits a Notify Response message including the P-GW ID(i.e., P-GW address) and an associated APN to the MME.

Supporting V2X Communication Via PC5 During IMS Emergency Call (eCall)

1. Principle for Applying Parameters for V2X Communication Via PC5Reference Point

For V2X communication over PC5, the operator may pre-configure the UEswith the provisioning parameters required for V2X Communication, withoutthe need for the UEs to connect to the V2X Control Function to obtain aninitial configuration.

The following matters are applied:

-   -   Provisioning parameters for V2X communication via PC5 may be        configured in the Universal Integrated Circuit Card (UICC) or in        the ME or both in the UICC and the ME.    -   When both the UICC and the ME contain a set of the same        provisioning parameters, the set of parameters takes precedence        from the UICC.    -   The UE uses resources for the V2X communication through the PC5        reference point as follows:    -   When the UE has the serving cell and the UE camps on the cell        and the UE intends to use a V2X service radio resource, the UE        uses the radio resource description indicated by the cell which        the UE camps on and ignores any radio resource description of        the same radio resource provisioned in the ME or the UICC. When        the cell does not provide the radio resource for the V2X        service, the UE does not perform V2X message transmission and        reception on the radio resource operated by the corresponding        cell.    -   When the UE intends to the radio resource (i.e. carrier        frequency) for V2X service that are not operated by the UE's        serving cell or if the UE is out of coverage, the UE searches        for a cell in any PLMN that operates the provisioned radio        resources (i.e. carrier frequency).    -   When the UE finds the cell in the registered PLMN or the PLMN        equivalent to the registered PLMN and is authorized for the V2X        communication via the PC5 reference point by the PLMN, the UE        uses the radio resource description indicated by the        corresponding cell. When the cell does not provide the radio        resource for the V2X service, the UE does not perform V2X        message transmission and reception on the radio resource.    -   When the UE finds the cell in the registered PLMN or PLMN other        than the PLMN equivalent to the registered PLMN, the        corresponding cell belongs to PLMN authorized for the V2X        communication through the PC5 reference point, and the        corresponding cell provides the radio resource for the V2X        service, the UE performs PLMN selection triggered by the V2X        communication via the PC5 reference point. When the UE has        activated emergency PDN connectivity, this does not trigger any        PLMN selection due to the V2X communication through the PC5        reference point.    -   When the UE finds the cell the PLMN other than the PLMN        authorized for the V2X communication through the PC5 reference        point, the UE does not use the V2X communication through the PC5        reference point.    -   When the UE does not find any cell in any PLMN, it is regarded        that the UE is “not served by E-UTRAN” and uses the provisioned        radio resource in the ME or the UICC. If no such provisioning        exists in the ME or the UICC or the provisioning is not        authorized in the V2X communication over PC5 reference point,        the UE is not authorized for transmission.    -   UE provisioning supports setting of Geographical Areas.    -   The V2X communication through the PC5 reference point is limited        only for the E-UTRA.

2. V2X Message Transmission/Reception Via PC5 Reference Point

The PC5 reference point is used for transmission and reception of theV2X message. The V2X communication via the PC5 reference point supportsroaming and an inter-PLMN operation. When the UE is served by E-UTRANand not served by E-UTRAN, the V2X communication via the PC5 referencepoint is supported.

The UE is authorized to transmit and receive the V2X message by the V2XControl Function in the home PLMN of the UE.

The V2X communication via the PC5 reference point is a type of ProSedirect communication having the following features:

-   -   The V2X communication via the PC5 reference point is        connectionless and has no signaling through a PC5 control plane        for connection establishment.    -   The V2X message is exchanged between PC5 user planes.    -   Both IP based and non-IP based messages are supported.    -   In the case of the IP based V2X message, only IP version 6        (IPv6) is used and IP version 4 (IPv4) is not supported.

When the UE has the activated emergency PDN connection, thecommunication over the emergency PDN connection is prioritized over theV2X communication over the PC5 reference point based onregional/national regulatory requirements and operator policies.

3. Supporting V2X Communication for UE in Limited Service State

In the case of the UE in the limited service state, only the V2Xcommunication via the PC5 reference point is allowed.

The UE that is authorized to use the V2X communication over the PC5reference point may use the V2X communication over the PC5 referencepoint in accordance with the principle defined for the V2X communicationover the PC5 reference point when the UE is in the limited servicestate. The UE enters the limited service state in the followingsituations:

-   -   when the UE may not find the suitable cell in the selected PLMN;        or    -   when a “PLMN not allowed”/“GPRS not allowed” response is        received with respect to a registration request;

The UE in the limited service state may use the V2X communication overthe PC5 reference point in the ECM-IDLE mode.

The UE does not use V2X communication over PC5 reference point, if theUE has entered in the limited service state due to all other situations(e.g., when there is no SIM in the MS, when receiving an “illegal MS” or“illegal ME” response to a registration request, or when receiving an“IMSI unknown in HLR” response to a registration request). In this case,the UE may not receive a general service from the PLMN.

Clarification for V2X Communication Over PC5 in Limited Service State

1. Policy/Parameter Provisioning

The following information is provisioned to the UE for the V2Xcommunication via the PC5 reference point:

1) Authorization Policy

When the UE is “served by E-UTRAN”: PLMNs in which the UE is authorizedto perform V2X communications over PC5 reference point.

-   -   When the UE is “not served by E-UTRAN”: Indicates whether the UE        is authorized to perform V2X communications over PC5 reference        point when “not served by E-UTRAN”.

Radio parameters for when the UE is “not served by E-UTRAN”:

-   -   Includes the radio parameters with Geographical Area(s) that to        enable the UE to perform V2X communications over PC5 reference        point when the UE is “not served by E-UTRAN”. These radio        parameters (e.g., frequency bands) contain an indication of        whether they are “operator managed” or “non-operator managed”.        The UE uses the radio parameters only when the UE may reliably        locate itself in the corresponding Geographical Area. Otherwise,        the UE is not authorized to transmit.

3) Policy/Parameters for V2X Communication Over PC5 Reference Point:

-   -   The mapping of Destination Layer-2 ID(s) and the V2X services.    -   The mapping of ProSe Per-Packet Priority and packet delay budget        for V2X communication (autonomous resources selection mode).

2. Principle for Applying Parameters for V2X Communication Via PC5Reference Point

For V2X communication over PC5, the operator may pre-configure the UEswith the provisioning parameters required for V2X Communication, withoutthe need for the UEs to connect to the V2X Control Function to obtain aninitial configuration.

The following matters are applied:

-   -   Provisioning parameters for V2X communication via PC5 may be        configured in the Universal Integrated Circuit Card (UICC) or in        the ME or both in the UICC and the ME.    -   The ME provisioning parameters are not be erased when a USIM is        deselected or replaced.    -   When both the UICC and the ME contain a set of the same        provisioning parameters, the set of parameters takes precedence        from the UICC.    -   The UE uses resources for the V2X communication through the PC5        reference point as follows:    -   When a UE has a serving cell and is camped on a cell and the UE        intends to use for V2X service the radio resources, the UE uses        the radio resource description indicated by the cell in which        the UE is camped on and ignores any radio resource description        of the same radio resource provisioned in the ME or the UICC.        When the cell does not provide the radio resource for the V2X        service, the UE does not perform V2X message transmission and        reception on the radio resource operated by the corresponding        cell.    -   If the UE intends to use “operator-managed” radio resources        (i.e. carrier frequency) for V2X service that are not operated        by the UE's serving cell or if the UE is out of coverage, the UE        searches for a cell in any PLMN that operates the provisioned        radio resources (i.e. carrier frequency).    -   When the UE finds the registered PLMN or such a cell in the PLMN        equivalent to the registered PLMN and is authorized for the V2X        communication via the PC5 reference point by the PLMN, the UE        uses the radio resource description indicated by the        corresponding cell. When the cell does not provide the radio        resource for the V2X service, the UE does not perform V2X        message transmission and reception on the radio resource.    -   When the UE finds the cell in the registered PLMN or PLMN other        than the PLMN equivalent to the registered PLMN, the        corresponding cell belongs to PLMN authorized for the V2X        communication through the PC5 reference point, and the        corresponding cell provides the radio resource for the V2X        service, the UE performs PLMN selection triggered by the V2X        communication via the PC5 reference point. When the UE has        activated emergency PDN connectivity, this does not trigger any        PLMN selection due to the V2X communication through the PC5        reference point.    -   When the UE finds the cell the PLMN other than the PLMN        authorized for the V2X communication through the PC5 reference        point, the UE does not use the V2X communication through the PC5        reference point.    -   If the UE does not find any such cell in any PLMN, the UE is        “not served by E-UTRAN” and uses radio resources provisioned in        the ME or the UICC. If no such provisioning exists in the ME or        the UICC or the provisioning is not authorized in the V2X        communication over PC5 reference point, the UE is not authorized        for transmission.

If the UE intends to use “non-operator-managed” radio resources (i.e.carrier frequency) for V2X service, the UE performs V2X communicationover PC5 using resources provisioned in the ME or the UICC. If no suchprovision exists in the ME or the UICC or the provision is notauthorized in the V2X communication over PC5 reference, the UE is notauthorized to transmit.

-   -   UE provisioning supports setting of Geographical Areas.    -   The V2X communication through the PC5 reference point is limited        only for the E-UTRA.

For example, when the UE is in coverage of a 3GPP RAT, the UE maydetermine that the UE is located in a specific geographical area byusing information derived from the serving PLMN. When the UE is not incoverage of the 3GPP RAT, the UE may determine that the UE is located ina specific geographical area by using other techniques (e.g., GlobalNavigation Satellite System (GNSS)).

3. Supporting V2X Communication for UE in Limited Service State

In the case of the UE in the limited service state, only the V2Xcommunication via the PC5 reference point is allowed.

The UE that is authorized to use the V2X communication over the PC5reference point may use the V2X communication over the PC5 referencepoint in accordance with the principle defined for the V2X communicationover the PC5 reference point when the UE is in the limited servicestate. The UE enters the limited service state in the followingsituation:

-   -   when the UE may not find the suitable cell in the selected PLMN;        or    -   when a “PLMN not allowed”/“GPRS not allowed” response is        received with respect to a registration request;

A UE in the limited service state only use the radio resources andprocedure available in the ECM-IDLE mode for V2X communication over PC5reference point.

The UE in the limited service state does not use V2X communication overPC5 reference point in the ECM-CONNECTED mode.

UEs do not use V2X communication over PC5 reference point using“operator-managed” radio resources, if the UE has entered in the limitedservice state due to all other situations (e.g., when there is no SIM inthe MS, when receiving an “illegal MS” or “illegal ME” response to aregistration request, or when receiving an “IMSI unknown in HLR”response to a registration request). In this case, the UE may notreceive a general service from the PLMN. The UEs may use V2Xcommunication over PC5 reference point using the “non-operator-managed”radio resources.

Handling of Emergency Calls in Limited Service Mode

According to the contents to be described below, when the UE is in thelimited service state, information indicating that the UE is in thelimited service state is included in an S1-AP message (e.g., InitialContext Setup Request message) provided to the eNB by the MME.

1. Initial Context Setup

The purpose of the Initial Context Setup procedure is to establish thenecessary overall initial UE Context, and the overall UE contextincludes an E-UTRAN Radio Access Bearer (E-RAB) context, a Security Key,a Handover Restriction List, a UE Radio capability, and a UE SecurityCapability, etc. The procedure uses UE-associated signaling.

FIG. 9 illustrates an initial context setup procedure in a wirelesscommunication system to which the present invention may be applied.

FIG. 9A illustrates a successful operation and FIG. 9B illustrates anunsuccessful operation.

1) Successful Operation

For E-RAB establishment, the MME needs to be prepared to receive userdata before the INITIAL CONTEXT SETUP RESPONSE message is received.

The INITIAL CONTEXT SETUP REQUEST message includes information requiredby the eNB to establish a new E-RAB configuration that includes at leastone additional E-RAB in an E-RAB to be Setup List IE.

The E-RAB to be Setup List IE may include the following.

-   -   NAS-PDU IE

The INITIAL CONTEXT SETUP REQUEST message may include the following:

-   -   Trace Activation IE    -   Handover Restriction List IE, in which IE may contain roaming,        area or access restrictions.    -   UE Radio Capability IE    -   Subscriber Profile ID for RAT/Frequency priority IE    -   CS Fallback Indicator IE        -   Single Radio Voice Call Continuity (SRVCC) Operation            Possible IE

The INITIAL CONTEXT SETUP REQUEST message may include a SubscriberProfile ID for RAT/Frequency priority IE if available in the MME.

When receiving the INITIAL CONTEXT SETUP REQUEST message, the eNBoperates as follows:

-   -   The eNB attempts to execute the requested E-RAB configuration.    -   The eNB stores a UE Aggregate Maximum Bit Rate (AMBR) in the UE        context, and use the received UE AMBR for a non-Guaranteed Bit        Rate (non-GBR) bearer for the corresponding UE.    -   The eNB transfers a value contained in the E-RAB ID IE and the        NAS-PDU IE received for the E-RAB for each established data        radio bearer to the radio interface protocol. The eNB does not        transmit an NAS PDU associated with an unsuccessful data radio        bearer to the UE.

Further, the eNB stores the received Handover restriction List in the UEcontext.

Further, the eNB stores the received UE Radio Capability in the UEcontext.

-   -   The eNB stores the received Subscriber Profile ID for        RAT/Frequency priority in the UE context.    -   The eNB stores the received SRVCC operation possible in the UE        context.    -   The eNB stores the received UE Security Capabilities in the UE        context.    -   The eNB stores the received Security Key in the UE context.

For the Initial Context Setup, a value for a Next Hop Chaining Count isstored in the UE context.

Allocation of resources according to values of the Allocation andRetention Priority IE follows the principles described for the E-RABSetup procedure.

The eNB uses the information in the Handover Restriction List IE todetermine a target cell for handover if the Handover Restriction List IEis present in the INITIAL CONTEXT SETUP REQUEST message. If the HandoverRestriction List IE is not contained in the INITIAL CONTEXT SETUPREQUEST message, the target eNB considers that the roaming area or theaccess restriction is not applied to the UE.

If the Trace activation IE is included in the INITIAL CON TEXT SETUPREQUEST message, the eNB, if supported, initiates the requested tracefunction.

If the CS Fallback Indicator IE is included in the INITIAL CONTEXT SETUPREQUEST message, it indicates that the UE Context to be setup issubjected to CS Fallback.

If the UE Security Capabilities IE included in the INITIAL CONTEXT SETUPREQUEST message contains only an EIAO algorithm and the EIAO algorithmis defined in the configured list of allowed integrity protectionalgorithms in the eNB, the eNB uses the corresponding algorithms andignores the keys received in the Security Key IE.

The eNB reports to the MME, in the INITIAL CONTEXT SETUP RESPONSEmessage, the successful establishment of the security procedures withthe UE, and the result for all the requested E-RABs in the followingmethod:

-   -   A list of E-RABs which are successfully established is included        in an E-RAB Setup List IE.    -   A list of E-RABs which failed to be established is included in        an E-RAB Failed to Setup List IE.

When the eNB reports the unsuccessful establishment of the E-RAB, thecause value needs to be precise enough to enable the MME to know thereason for the unsuccessful establishment (e.g., “Radio resources notavailable”, “Failure in the Radio Interface Procedure”, etc.).

After transmitting the INITIAL CONTEXT SETUP RESPONSE message, theprocedure is terminated in the eNB.

2) Unsuccessful Operation

When the eNB may not establish the S1 UE context, or when the eNB maynot also establish one non-GBR bearer, the eNB regards the procedure asfailed and responds with the INITIAL CONTEXT SETUP FAILURE message.

3) Abnormal Conditions

If the eNB receives an INITIAL CONTEXT SETUP REQUEST message whichcontains an E-RAB Level QoS Parameters IE which contains a QoS ClassIdentifier (QCI) IE indicating a GBR bearer and an E-RAB Level QoSParameters IE without containing the GBR QoS Information IE, the eNBconsiders the establishment of the corresponding E-RAB as failed.

If the eNB receives an INITIAL CONTEXT SETUP REQUEST message containingseveral E-RAB ID IEs (in the E-RAB to Be Setup List) set to the samevalue, the eNB considers the establishment of the corresponding E-RABsas failed.

If the algorithms supported for encryption are defined in the EncryptionAlgorithms IE in the UE Security Capabilities IE, but do not match anyallowed algorithms defined in the configured list of allowed encryptionalgorithms in the eNB, the eNB rejects the procedure using the INITIALCONTEXT SETUP FAILURE message.

If the algorithms supported for integrity are defined in the IntegrityProtection Algorithms IE in the UE Security Capabilities IE, but do notmatch any allowed algorithms defined in the configured list of allowedintegrity protection algorithms in the eNB, the eNB rejects theprocedure using the INITIAL CONTEXT SETUP FAILURE message.

2. UE Context Modification

The purpose of the UE Context Modification procedure is to partiallymodify the established UE Context (e.g., Security Key, SubscriberProfile ID for RAT/Frequency priority, etc.). The procedure usesUE-associated signaling.

FIG. 10 illustrates a UE context modification procedure in a wirelesscommunication system to which the present invention may be applied.

FIG. 10A illustrates a successful operation and FIG. 10B illustrates anunsuccessful operation.

1) Successful Operation

The UE CONTEXT MODIFICATION REQUEST message may contain the following:

-   -   Security Key IE    -   Subscriber Profile ID for RAT/Frequency priority IE    -   UE Aggregate Maximum Bit Rate IE    -   CS Fallback Indicator IE    -   UE Security Capabilities IE

When receiving the UE CONTEXT MODIFICATION REQUEST message, the eNBoperates as follows:

-   -   The eNB stores the received Security Key IE, the Security Key IE        is used as the initial value of a Next Hop Chaning Counter        (NCC).    -   The eNB stores the received UE Security Capabilities IE and use        it together with the received key when the EIAO algorithm is        used.    -   The eNB stores and uses the Subscriber Profile ID for        RAT/Frequency priority IE.

If the UE Aggregate Maximum Bit Rate IE is included in the UE CONTEXTMODIFICATION REQUEST, the eNB operates as follows:

-   -   UE Aggregate Maximum Bit Rate provided previously    -   replace the previously provided UE Aggregate Maximum Bit Rate by        the UE AMBR receiving the previously provided UE AMBR in the UE        context; the eNB uses the received UE AMBR for non-GBR Bearers        for the corresponding UE.

If the UE Aggregate Maximum Bit Rate IE is not contained in the UECONTEXT MODIFICATION REQUEST message, the eNB uses the previouslyprovided UE AMBR which is stored in the UE context.

If the CS Fallback Indicator IE is included in the INITIAL CONTEXT SETUPREQUEST message, it indicates that the corresponding UE Context issubjected to CS Fallback.

The eNB reports, in the UE CONTEXT MODIFICATION RESPONSE message, to theMME, the successful update of the UE context as follows:

After transmitting the UE CONTEXT MODIFICATION RESPONSE message, theprocedure is terminated in the eNB.

2) Unsuccessful Operation

When the UE context update cannot be performed successfully, the eNBtransmits the UE CONTEXT MODIFICATION FAILURE message to the MME with anappropriate cause value in the Cause IE.

3. Handover Resource Allocation

The purpose of the Handover Resource Allocation procedure is to reserveresources at the target eNB for the handover of a UE.

FIG. 11 illustrates a handover resource allocation procedure in awireless communication system to which the present invention may beapplied.

FIG. 11A illustrates a successful operation and FIG. 11B illustrates anunsuccessful operation.

1) Successful Operation

The MME initiates the procedure by transmitting a HANDOVER REQUESTmessage to the target eNB. The HANDOVER REQUEST message may contain aHandover Restriction List IE, which contains a roaming area or accessrestrictions.

If the Handover Restriction List IE is contained in the HANDOVER REQUESTmessage, the target eNB stores this information in the UE context.

The eNB uses the information in the Handover Restriction List IE todetermine a target cell for handover if the Handover Restriction List IEis present in the HANDOVER REQUEST message. If the Handover RestrictionList IE is not contained in the HANDOVER REQUEST message, the target eNBconsiders that the access restriction is not applies to the UE.

When receiving the HANDOVER REQUEST message, the eNB stores the receivedUE Security Capabilities IE in the UE context and uses the stored UESecurity Capabilities IE to prepare the configuration of the AS securityrelated with the UE.

If a SRVCC Operation Possible IE is included in the HANDOVER REQUESTmessage, the target eNB stores the received SRVCC operation possible IEin the UE context and uses the stored SRVCC operation possible IE.

When receiving the HANDOVER REQUEST message, the eNB stores the receivedSecurity Context IE in the UE context and uses the stored SecurityContext IE to derive the security configuration.

If the Trace activation IE is included in the HANDOVER REQUEST message,the target eNB initiates the requested trace function.

If the Subscriber Profile ID for RAT/Frequency priority IE is containedin a Source eNB to Target eNB Transparent Container IE, the target eNBstores the received Subscriber Profile ID for RAT/Frequency priority inthe UE context.

When receiving a UE History Information IE, which is included in theSource eNB to Target eNB Transparent Container IE in the HANDOVERREQUEST message, the target eNB collects the information in the UEHistory Information IE while the UE stays in one of its cells, and usesthe collected information for future handover preparations.

After all required resources for the admitted E-RABs have beenallocated, the target eNB generates a HANDOVER REQUEST ACKNOWLEDGEmessage. The target eNB includes an E-RABs Admitted List IE in whichresources have been prepared at the target cell. The E-RABs that havenot been admitted in the target cell are included in an E-RABs Failed toSetup List IE.

For each bearer that target eNB has decided to admit and for which DLforwarding IE is set to “DL forwarding proposed”, the target eNB mayinclude a DL GPRS Tunnelling Protocol (GTP)-Tunnel endpoint identifier(TEID) IE indicating that it accepts the proposed forwarding of downlinkdata for this bearer and a DL Transport Layer Address IE in the E-RABsAdmitted List IE in the HANDOVER REQUEST ACKNOWLEDGE.

If the HANDOVER REQUEST ACKNOWLEDGE message contains UL GTP-TEID IE andUL Transport Layer Address IE for a bearer in the E-RABs Admitted ListIE, the target eNB requests forwarding of uplink data for this bearer.

If the Request Type IE is included in the HANDOVER REQUEST message, thetarget eNB performs the requested location reporting function for theUE.

If the UE Security Capabilities IE including only the EIAO algorithm isincluded in the HANDOVER REQUEST message and if the EIAO algorithm isdefined in the configured list of allowed integrity protectionalgorithms in the eNB, the eNB uses the corresponding algorithm andignores the keys received in the Security Context IE.

2) Unsuccessful Operation

If the target eNB does not admit at least one non-GBR E-RAB, or afailure occurs during the Handover Preparation, the target eNB transmitsthe HANDOVER FAILURE message to the MME with an appropriate cause value.

If the target eNB receives a HANDOVER REQUEST message containing an RRCContainer IE that does not include required information, the target eNBtransmits the HANDOVER FAILURE message to the MME.

3) Abnormal Conditions

If the eNB receives a HANDOVER REQUEST message containing a E-RAB LevelQoS Parameters IE which contains a QCI IE indicating a GBR bearer anddoes not contain the GBR QoS Information IE, the eNB does not accept thecorresponding E-RAB.

If the eNB receives a HANDOVER REQUEST message containing several E-RABID IEs (in the E-RAB to Be Setup List) set to the same value, the eNBdoes not accept the corresponding E-RAB.

If the Subscriber Profile ID for RAT/Frequency priority IE is notcontained in the Source eNB to Target eNB Transparent Container IE, thetarget eNB shall trigger a local error handling.

If the supported algorithms for encryption defined in the EncryptionAlgorithms IE in the UE Security Capabilities IE are not matched withany allowed algorithms defined in the configured list of allowedencryption algorithms in the eNB, the eNB rejects the procedure usingthe HANDOVER FAILURE message.

If the supported algorithms for integrity defined in the IntegrityProtection Algorithms IE in the UE Security Capabilities IE are notmatched with any allowed algorithms defined in the configured list ofallowed integrity protection algorithms in the eNB, the eNB rejects theprocedure using the HANDOVER FAILURE message.

Table 8 shows the UE CONTEXT MODIFICATION REQUEST message.

This message is transmitted by the MME to provide changes in UE Contextinformation to the eNB.

TABLE 8 IE type IE/Group and Assigned Name Presence Range referenceSemantics description Criticality Criticality Message Type M 9.2.1.1 YESreject MME UE M 9.2.3.3 YES reject S1AP ID eNB UE S1AP M 9.2.3.4 YESreject ID Security Key O 9.2.1.41 A new KeNB is YES reject providedafter a key change procedure in the MME is performed. Subscriber O9.2.1.39 YES ignore Profile ID for RAT/Frequency priority UE Aggregate O9.2.1.20 YES ignore Maximum Bit Rate CS Fallback O 9.2.3.21 YES rejectIndicator UE Security O 9.2.1.40 YES reject Capabilities

Referring to Table 8, the IE/Group Name represents the name of an IE oran information element group (IE group). ‘M’ in a Presence field as amandatory IE represents an IE/IE group always included in the message,and ‘0’ as an optional IE represents an IE/IE group that may be includedin the message or not included in the message, and ‘C’ represents as aconditional IE represents an IE/IE group included in the message onlywhen a specific condition is satisfied. A Range field represents thenumber of repetitive IEs/IE groups which may be repeated.

An IE type and reference field represents a type (e.g., ENUMERATED data,INTEGER, OCTET STRING, etc.) of the corresponding IE and represents arange of a value when the range of a value which the corresponding IEmay have exists.

A Criticality field represents criticality information applied to theIE/IE group. The criticality information refers to informationindicating how a receiver should operate in the case where the receiverdoes not understand the entirety or a part of the IE/IE group. ‘-’represents that the criticality information is not applied and ‘YES’represents that the criticality information is applied. ‘GLOBAL’indicates that there is one criticality information common to the IE andrepetition of the corresponding IE. ‘EACH’ indicates that there isunique criticality information for each repetition of the IE. AnAssigned Criticality field indicates actual criticality information.

The detailed description of the information element (IE) or the IE groupincluded in the UE CONTEXT MODIFICATION REQUEST message has beendescribed above and thus will be omitted.

Table 9 shows the UE Security Capabilities IE.

This IE defines the supported algorithms for encryption and integrityprotection in the UE.

TABLE 9 IE/Group Name UE Security IE type and Capabilities PresenceRange reference Semantics description >Encryption M Bit string Eachposition in the bitmap Algorithms (16, . . .) represents an encryptionalgorithm: “all bits equal to 0” - UE supports no other algorithm thanEEA0 “first bit” - 128-EEA1, “second bit” - 128-EEA2, other bits arereserved. Value ‘1’ indicates support of the algorithm and value ‘0’indicates no support of the algorithm. >Integrity M Bit string Eachposition in the bitmap Protection (16, . . .) represents an integrityprotection Algorithms algorithm: “all bits equal to 0” - UE supports noother algorithm than EIA0 “first bit” - 128-EIA1, “second bit” -128-EIA2, other bits are reserved. Value ‘1’ indicates support of thealgorithm and value ‘0’ indicates no support of the algorithm.

Method for Performing V2X Communication Via PC5 (i.e., UE-to-UE RadioInterface) by UE in Limited Service State

1) Problem 1

According to the operation in the related art, the UE in the limitedservice state may perform attach for the emergency bearer service. Whenthe attach for the emergency bearer service is successfully performed,the UE may use the emergency bearer service in the EMM-CONNECTED state.

However, in the attach for emergency bearer service, the process ofdelivering the UE context related to the V2X service of the UE to theeNB by the MME is not performed. Accordingly, even though the attach foremergency bearer service is performed, the eNB does not have the contextrelated to the V2X service of the UE.

In this case, when the UE desires to perform the V2X communication overPC5, the UE needs to request a radio resource for the V2X communicationover PC5 to the eNB because the UE is in the EMM-CONNECTED state. Tothis end, the UE (AS layer) transmits the sidelink UE informationmessage to the eNB (base station).

However, since the eNB receiving the sidelink UE information messagedoes not have the V2X service related UE context for the correspondingUE, the eNB may not confirm the V2X related authorization/capability forthe UE. Therefore, the eNB may not accept the response to the sidelinkUE information message. That is, the eNB may provide the radio resourcefor the V2X communication to the UE.

As a result, the UE may not perform the V2X communication over PC5because the UE is not allocated the radio resource for the V2Xcommunication over PC5.

In general, in the V2X service, the vehicle (i.e., vehicle UE) transmitsa periodic V2X message (e.g., generally transmits the periodic V2Xmessage every 10 times per second in order to announce a position, aspeed, and existence of the vehicle) and transmits the V2X message(e.g., announcement of brake failure, accident announcement, etc.) tonearby vehicles by using the PC5 even when an event occurs. However,when an accident occurs in any vehicle, if the emergency call isinitiated in the limited service state, the V2X message may not betransmitted to the surrounding vehicles while the emergency call isongoing.

2) Problem 2

According to the operation in the related art, when a cell on which theUE in the limited service state and the EMM-IDLE state camps sends V2Xrelated information to broadcasting information, but does not broadcasta resource pool for V2X message transmission (i.e., when the UEestablishes the RRC connection with the eNB and the corresponding UE hasto transmit the V2X message through a dedicated resource for itself),the UE needs to switch to EMM-CONNECTED and request the V2Xcommunication to the eNB in order to perform the V2X communication.

However, since the UE in the limited service state may not performlocation registration (LR) other than the attach for the emergencybearer service, the UE may switch to EMM-CONNECTED. Accordingly, the UEmay not request the radio resource for the V2X communication to the eNB,and as a result, the UE may not perform the V2X communication.

3) Problem 3

In a scenario of Problem 1 described above, according to the operationin the related art, the UE in the limited service state may successfullyperform the attach for the emergency bearer service and switch toEMM-CONNECTED for the emergency bearer service.

In this case, the UE should satisfy a precondition described in 3GPP TS24.386 in order to perform the V2X communication via the PC5 (see theV2X communication and the limited service state described above).

However, the PLMN in which the UE is registered may not be included inan authorized PLMN list (i.e., the list of PLMNs in which the UE isauthorized to use the V2X communication over PC5 when the UE is “servedby E-UTRAN”). In this case, the UE may not perform the V2X communicationover PC5. As a result, the V2X message may not be generated in the V2Xlayer of the UE or the sidelink UE information message may not betransmitted in the RRC layer.

4) Problem 4

According to the related art, the operation of performing the V2Xcommunication over PC5 when the UE is “Not served by E-UTRAN” isdescribed (see one-to-many Prose direct communication transmission notserved by the E-UTRAN above).

In this case, the UE may perform PLMN selection triggered by ProSedirect communication specified by 3GPP TS 23.122 when interferenceexists through an interference check for a configured radio parameter.

In the ProSe direct communication, only one frequency (carrier) for theProSe direct communication exists.

On the contrary, in the case of the V2X communication over PCS, one ormore frequencies may be configured. In this case, when interferenceexists at a specific frequency, if the UE performs PLMN selection,unnecessary signaling overhead and service support occur.

5) Problem 5

When the UE performs both the V2X communication over PC5 and a normalservice (e.g., IMS call) over LTE-Uu, which service of two services isperformed first is discussed and the following operation is proposed.

When the uplink transmission (UL TX) in the time domain overlaps withsidelink transmission (SL TX) within the shared (or the same) carrierfrequency, if a ProSe priority per packet (PPPP) for each packet of anSL packet exceeds a (pre)configured PPPP threshold value, the UE dropsthe UL TX and otherwise, the UE drops the SL TX.

The above contents may be interpreted as the PPPP threshold value beingconfigured and if a PPPP is higher than the PPPP threshold value, thesidelink is first transmitted and otherwise, the uplink is firsttransmitted.

When it is assumed that the service for the corresponding LTE-Uu (UL TX)is the emergency call, if a packet for the LTE-Uu (UL TX) is droppedaccording to the above proposal, the emergency call may not beperformed.

As an alternative thereto, when the emergency call occurs, an operationof processing prior to the V2X communication over PC5 is proposed. Thatis, when the UE has an active emergency PDN connection, thecommunication over the LTE-Uu takes precedence over the V2Xcommunication over PC5.

In order to perform such an operation, the eNB needs to know that thecorresponding UE is in an emergency service.

However, when the emergency PDN connection is generated in theEMM-CONNECTED mode, the eNB may not recognize that the UE is in theemergency service, and as a result, an operation is proposed in whichthe MME announces that the UE is in the emergency service to the eNBwhen the PDN connection is an emergency PDN type. That is, when the UEis authorized for the V2X communication and begins to establish theemergency PDN connection, the MME announces to the eNB that theemergency connection for the UE is established. In such a procedure, anoperation in the network (eNB) is proposed.

However, in such a proposal, an additional S1-AP signaling operationoccurs as compared with the related art. In addition, in this case,signaling of a radio interval for requesting the resource for the V2Xmessage may not be reduced. Even when a cooperative awareness message(CAM) is generated in the UE which is in the emergency bearer service,the UE needs to transmit a sidelink buffer status report (BSR) forrequesting the resource for the CAM to the eNB. Accordingly, unnecessarysignaling and radio resources are wasted due to the sidelink BSR for theCAM which is not particularly sent in the emergency situation.

6) Problem 6

According to the related art, the following points are agreed in 3GPPSA.

“When the UE has an active emergency PDN connection, the communicationover the emergency PDN connection is prioritized over the V2Xcommunication over a PC5 reference point based on regional/nationalregulatory requirements and operator policies.” (see V2X communicationsupport over PC5 during IMS emergency call (eCall) described above).

In 3GPP RAN2, a discussion related to prioritization of LTE-Uu and PCTtransmissions is in progress. For prioritization between the emergencyPDN connection and the V2X communication over PC5, the followinginformation is required in the RRC layer of the UE.

1) Whether the UE has the emergency PDN connection

2) whether the communication over the emergency PDN connection needs tobe prioritized over the V2X communication over the PC5 reference pointbased on regional/national regulatory requirements and operator policies

Referring to 1) above, when the UE performs the attach for the emergencyPDN connection in the EMM-IDLE mode, the NAS layer of the UE delivers anRRC establishment cause to the RRC layer of the UE together with anattach request message. In this case, since the ‘emergency call’ isdisplayed in the RRC establishment cause, the RRC layer of the UE mayrecognize that there is the emergency PDN connection. However, when theUE establishes the emergency PDN connection in the EMM-CONNECTED mode,since the NAS layer of the UE does not deliver the RRC establishmentcause to the RRC layer of the UE, the RRC layer of the UE does notrecognize the RRC establishment cause.

Referring to 2) described above, the corresponding information may be(pre)configured in the UE. However, the RRC layer of the UE may not knowthe set value.

In order to solve such a problem, the present invention intends topropose a method for performing the V2X communication over PC5 by the UEin the limited service state.

Hereinafter, in the description of the present invention, with respectto a resource allocation mode, Mode 3 means a mode in which the eNB(base station) providing the V2X service (e.g., V2X communication)dynamically allocates a specific resource to be used by the UE and theUE confirms the physical channel, confirms a resource to be usedthereby, and then, performs transmission by using the correspondingresource.

Mode 4 refers to a mode in which the UE autonomously transmit themessage by selecting the resource for transmission after receiving oneor multiple transmission resource pools from the network.

As a result, Mode 4 is referred to as a UE autonomous resource selectionmode and Mode 3 is referred to as a scheduled resource allocation mode.

Further, hereinafter, in the description of the present invention, a V2Xcommunication capability refers to a capability to perform the V2Xcommunication over PC5. The V2X communication over PC5 may refer toperforming the V2X communication over PC5 interface and may be referredto as V2X sidelink communication.

Embodiment 1

In an embodiment of the present invention, proposed is a method forperforming the V2X communication over PC5 by the UE which is in thelimited service state and the EMM-CONNECTED mode in order to solve theproblems described in Problems 1 and 3 above.

Embodiment 1-1

In Embodiment 1-1, when the UE transmits a sidelink UE informationmessage to the eNB, the eNB may allocate the resource for the V2Xcommunication for a UE (i.e., a UE which is the EMM-CONNECTED mode andusing an emergency service) which is in the emergency service.

FIG. 12 is a diagram illustrating a method for performing V2Xcommunication over PC5 according to an embodiment of the presentinvention.

0. The UE in the limited service state starts the attach procedure forthe emergency bearer service. That is, the attach message is generated.

1. When the UE in the limited service state performs the attach for theemergency bearer service, the NAS layer of the UE generates the RRCestablishment cause and/or indication and delivers the generated RRCestablishment cause and/or indication to the AS layer of the UE togetherwith the attach message as follows.

The AS layer of the UE uses the received RRC establishment cause and/orindication at the time of transmitting the RRC connection requestmessage.

I. The NAS layer of the UE may deliver the emergency call as the RRCestablishment cause to the AS layer of the UE.

II. In this case, the NAS layer of the UE may deliver a ‘V2Xcommunication’ indication indicating that there is the V2X communicationcapability.

III. The RRC establishment cause or indication may be implemented byindividual values such as the ‘emergency call’ and the ‘V2Xcommunication’ and may be implemented by a third value (i.e., a singlevalue) including meanings of the two values. In the latter case, as anexample, the RRC establishment cause or indication may be implemented byan ‘emergency call with V2X communication capability’.

The AS layer of the UE performs a random access (RA) procedure.

2. The AS layer of the UE includes the corresponding RRC establishmentcause and/or indication in the RRC Connection Request message (i.e., theRA message (msg) 3) and transmits the RRC establishment cause and/orindication to the eNB.

Thereafter, the AS layer of the UE receives an RRC Connection Setupmessage (i.e., RA msg 4) from the eNB. In addition, the AS layer of theUE transmits an RRC Connection Complete message to the eNB, therebycompleting the random access procedure.

3. The eNB receiving the RRC establishment cause and/or indication inthe RRC Connection Request message may confirm (check) that the UE hasthe V2X communication capability in the following method. In addition,the eNB confirms (checks) the V2X communication capability and storesthe confirmed (checked) V2X communication capability.

I. When information indicating that there is the V2X communicationcapability is included in the indication (e.g., ‘V2X communication’)and/or the RRC establishment cause in the corresponding RRC connectionrequest message, the eNB may confirm (check) the V2X communicationcapability of the corresponding UE through the corresponding indicationand/or RRC establishment cause.

In this case, the eNB may perform a method of Embodiment 3 describedlater to verify (i.e., double check) the V2X communication capability ofthe corresponding UE.

II. When the information indicating that there is the V2X communicationcapability is not included in the indication (e.g., ‘V2X communication’)and/or the RRC establishment cause in the corresponding RRC connectionrequest message, the eNB may confirm the V2X communication capability ofthe corresponding UE through Embodiment 3 described later.

As illustrated in FIG. 12, the MME accepts the attach of the UE totransmit an Attach Accept message to the NAS layer of the correspondingUE. By receiving the Attach Accept message, the UE enters theEMM-CONNECTED mode and starts the emergency service. In FIG. 12, adetailed Attach procedure is omitted.

4. In the case where the corresponding RRC connection request isaccepted, when the UE indicates an ‘emergency call’ as the RRCestablishment cause in step 1 above, the eNB may store that thecorresponding UE is using the ‘emergency service’.

Further, when it is confirmed in step 3 that there is the V2Xcommunication capability for the corresponding UE, the eNB may storethat the corresponding UE has the V2X communication capability.

On the contrary, when the eNB rejects the RRC connection Request of theUE, the eNB may not store information on the corresponding UE.

Further, when the emergency bearer service ends later (i.e., when the UEswitches to EMM-IDLE or RRC-IDLE), the eNB may delete memory information(i.e., information indicating that the ‘emergency service’ is usingand/or the information indicating that there is the V2X communicationcapability) for the corresponding UE.

5. When the UE in the limited service state and the EMM-CONNECTED modeintends to perform the V2X communication over PCS, the UE transmits theSidelink UE information message to the eNB.

I. Triggering conditions for the Sidelink UE information messagetransmission of UE may be as follows.

A. When an application (APP) layer (i.e., V2X layer) of the UE transmitsthe V2X message to a lower layer (e.g., the NAS layer or the AS layer),information on the corresponding V2X message may be delivered. As anexample of the information on the corresponding message, a specialindication (or a V2X service indication) (e.g., ‘DecentralizedEnvironmental Notification Message (DENM)’ or ‘emergency’ or ‘publicsafety’) or a specific PPPP value may be transferred.

For operation A described above, in the case where the NAS layer or theRRC layer of the UE is using the emergency bearer service in the limitedservice state and has a capability for the V2X communication, the NASlayer or the RRC layer of the UE may inform the application layer of thecase where the NAS layer or the RRC layer of the UE is using theemergency bearer service in the limited service state and has thecapability for the V2X communication. As an example, when the attachaccept message is received, such an announcement operation may beperformed.

The application layer receiving such an operation may perform operationA described above. That is, the application layer may provide to thelower layer information (a special indication or service indication) onthe V2X message or provide the specific PPPP value while performingoperation A.

B. Even though the AS layer receiving the information or the specificPPPP value is currently in the limited service state, the AS layertransmits the Sidelink UE information message to the eNB.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the AS layer may transmit the Sidelink UE information messageto the eNB. In other words, only when the AS layer has a (pre)configuredor provisioned PPPP value and receives the corresponding PPPP value fromthe application layer, the AS layer may transmit the Sidelink UEinformation message to the eNB. In this case, a specific value may be(pre)configured or provisioned to a range (e.g., the specific PPPP valueor more).

C. In A above, when the corresponding V2X message is not the specialmessage or not the message corresponding to the specified PPPP value,the application layer may not provide but discard the corresponding V2Xmessage to the lower layer (e.g., the NAS layer or the AS layer). Inthis case, operations A and B described above are not performed.

II. In step 3 above, when I or II is not implemented (i.e., when the‘method for confirming the V2X communication capability of the UE’ isnot implemented), the following additional operation may be performed.

The UE may encapsulate in the corresponding Sidelink UE informationmessage the indication (i.e., the indication indicating that the UE hasthe emergency PDN connection) indicating that the ‘emergency service’ isusing and/or the special indication (or service indication) (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’). Further, the indication maybe an indication for announcing that the corresponding UE is in thelimited service state.

6. The eNB may confirm the V2X communication capability of the UE or aninterest of the UE in the V2X communication through the receivedSidelink UE information message.

Further, in this case, the eNB may perform Embodiment 3 in order toverify (double check) the V2X communication capability.

7. The eNB receiving the Sidelink UE information message may provide aV2X communication radio resource for the corresponding UE in thefollowing cases.

I. Case of confirming that the corresponding UE is in the ‘emergencyservice’,

II. Case of confirming that the corresponding UE is in the ‘emergencyservice’ and has the V2X communication capability,

III. Case of confirming that the corresponding UE is in the ‘emergencyservice’ and V2X service authorization, or

IV. Case of confirming that the corresponding UE is in the ‘limitedservice state’.

As the method described in the method of Embodiment 3 described later,the MME may explicitly announce that the UE is in the limited servicestate to the eNB or as in the related art, the eNB may implicitlyrecognize that the UE is in the limited service state (see ‘processingthe emergency call in the limited service mode’).

Embodiment 1-1 described above may operate without step 5-I-A. That is,even though the application layer does not deliver the specialindication or the specific PPPP value to the lower layer, the AS layerof the UE may transmit the Sidelink UE information message to the eNBeven with a transmission condition of the Sidelink UE Informationmessage in the related art.

Meanwhile, in the description of the present invention, a meaning that‘the eNB confirms the V2X communication capability’ includes a casewhere the MME provides V2X service authorization information to the eNBand the eNB checks whether the V2X service is authorized in the processof confirming the V2X communication capability when Embodiment 3 to bedescribed below is used.

Embodiment 1-2

In Embodiment 1-2, the UE may perform the V2X communication by using theTx resource pool for the V2X communication provided by the eNB withouttransmitting the Sidelink UE information.

FIG. 13 is a diagram illustrating a method for performing V2Xcommunication over PC5 according to an embodiment of the presentinvention.

I. The UE in the limited service state successfully performs the Attachprocedure for the emergency bearer service, and as a result, the UEswitches to the EMM-CONNECTED.

II. When the application layer of the UE transmits the V2X message tothe lower layer (i.e., NAS layer or V2X layer), information on thecorresponding V2X message may be delivered. As an example of theinformation on the corresponding message, a special indication (or a V2Xservice indication) (e.g., DENM or ‘emergency’ or ‘public safety’) or aspecific PPPP value may be delivered.

For the aforementioned operation, in the case where the NAS layer or theRRC layer of the UE is using the emergency bearer service in the limitedservice state and has a capability for the V2X communication, the NASlayer or the RRC layer of the UE may inform the application layer of thecase where the NAS layer or the RRC layer of the UE is using theemergency bearer service in the limited service state and has thecapability for the V2X communication. As an example, when the attachaccept message is received, such an announcement operation may beperformed.

The application layer receiving the attach accept message may performoperation II. That is, the application layer may provide to the lowerlayer information (a special indication or service indication) on theV2X message or provide the specific PPPP value while performingoperation II.

III. When the AS layer receiving the V2X message intends to perform theV2X communication over PC5, in the case where the eNB (base station)provides a next Tx resource pool, the AS layer may perform the V2Xcommunication over PC5 by using the Tx resource pool provided without aseparate process of requesting the Tx resource pool to the eNB.

A. For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the AS layer may transmit the Sidelink UE information messageto the eNB. In other words, only when the AS layer has a (pre)configuredor provisioned PPPP value and receives the corresponding PPPP value fromthe application layer, the AS layer may transmit the Sidelink UEinformation message to the eNB. In this case, a specific value may be(pre)configured or provisioned to a range (e.g., the specific PPPP valueor more).

B. The Tx resource pool may correspond to a resource pool (e.g.,commTxPoolNormalCommon or commTxPoolExceptional) broadcasted by the eNB.

In this case, the aforementioned resource pool may be used regardless ofa resource allocation mode (i.e., Mode 3 or Mode 4) of the UE.

Alternatively, the available resource pools may vary depending on theresource allocation mode as follows. For example, when the eNB sends V2Xrelated information as broadcast information, but does not broadcast aresource pool for transmission (i.e., when the UE establishes the RRCconnection with the eNB and cannot but transmit the V2X message for aresource dedicated for the UE) (i.e., in the case of Mode 3), thecommTxPoolExceptional may be used. On the contrary, in the case of Mode4, the commTxPoolExceptional or commTxPoolNormalCommon may be used.

IV. When the corresponding V2X message is not the special message or notthe message corresponding to the specified PPPP value, the applicationlayer may not provide but discard the corresponding V2X message to thelower layer (e.g., the NAS layer or the AS layer). In this case,operations II and III are not performed.

Embodiment 1-2 described above may operate without step II. That is,even though the application layer does not deliver the specialindication or the specific PPPP value to the lower layer, when the ASlayer satisfies an execution condition of the V2X communication overPC5, the AS layer may perform the V2X communication over PC5 by usingthe Tx resource pool.

Embodiment 2

An embodiment of the present invention proposes a method in which whenthe cell on which the UE camps sends the V2X related information as thebroadcast information, but does not broadcast the resource pool fortransmission (i.e., when the UE establishes the RRC connection with theeNB and cannot but transmit the V2X message through the resourcededicated for the UE), the UE in the limited service state and EMM-IDLE(or RRC-IDLE) performs the V2X communication over PC5, in order to solvethe problems described in Problem 2 above.

Embodiment 2-1

The UE switches to the EMM-CONNECTED (or RRC-CONNECTED) state andrequests the radio resource for the V2X communication to the eNB. Adetailed method is as follows.

When the UE in the limited service state and EMM-IDLE intends to performthe V2X communication over PC5, in the case where the cell on which theUE camps sends the V2X related information as the broadcast information,but does not broadcast the resource pool for transmission (that is, inthe case where the RRC connection is established and the V2X messagecannot but be transmitted through the dedicated resource for the UE),the UE switches to the EMM-CONNECTED or switches to RRC-CONNECTED &EMM-IDLE to perform the V2X communication over PC5. A specificdescription of each case is as follows.

(Case I) Operation when UE Switches to EMM-CONNECTED

When the UE switches to the EMM-CONNECTED, the UE may operate as one oftwo following methods.

-   -   Method A) The UE performs the Attach for the emergency bearer        service. In this case, the method described in [Embodiment 1-1]        is followed.    -   Method B) The UE performs not the Attach for the emergency        bearer service but the NAS procedure.

When Method A is performed, Method A may have the following differencefrom the method described in [Embodiment 1-1] described above.

1. When the UE intends to perform the V2X communication over PC5, in thecase where the cell on which the UE camps transmits the V2X relatedinformation as the broadcast information, but does not broadcast theresource pool for transmitting the V2X message (i.e., in the case wherethe UE establishes the RRC connection with the eNB and cannot buttransmit the V2X message through the dedicated resource for the UE), theUE initiates the Attach procedure for the emergency bearer service inorder to switch to the EMM-CONNECTED mode. In this case, conditions fortriggering the Attach procedure for the emergency bearer service may beas follows.

I. When the application layer (e.g., V2X layer) of the UE transmits theV2X message to the lower layer (i.e., NAS layer or AS layer), theinformation on the V2X message may be delivered. As an example of theinformation on the corresponding message, a special indication (or a V2Xservice indication) (e.g., ‘DENM’ or ‘emergency’ or ‘public safety’) ora specific PPPP value may be delivered.

For the aforementioned operation, in the case where the NAS layer or theRRC layer of the UE is using the emergency bearer service in the limitedservice state and has a capability for the V2X communication, the NASlayer or the RRC layer of the UE may inform the application layer of thecase where the NAS layer or the RRC layer of the UE is using theemergency bearer service in the limited service state and has thecapability for the V2X communication. As an example, when the attachaccept message is received, such an announcement operation may beperformed.

The application layer receiving such an operation may perform operationI described above. That is, the application layer may provide to thelower layer the information (a special indication or service indication)on the V2X message or provide the specific PPPP value while performingoperation I.

II. The NAS layer receiving the V2X message performs the above-describedNAS procedure.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the NAS procedure of the NAS layer may be triggered. In otherwords, only when the NAS layer has a (pre)configured or provisioned PPPPvalue and receives the corresponding PPPP value from the applicationlayer, the NAS procedure of the NAS layer may be triggered. In thiscase, a specific value may be (pre)configured or provisioned to a range(e.g., the specific PPPP value or more).

In this case, the interaction between the AS layer and the NAS layer mayoccur. For example, when the AS layer receives the special indication orPPPP value, the AS layer delivers the received special indication orPPPP value to the NAS layer to allow the NAS layer to trigger thecorresponding NAS procedure. Alternatively, the AS layer may deliver anindication that the V2X communication is required to the NAS layerinstead of delivering the received special indication or PPPP value asit is.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the NAS procedure of the NAS layer may be triggered. In otherwords, when the NAS layer has a (pre)configured or provisioned PPPPvalue and receives the corresponding PPPP value from the applicationlayer, the AS layer may trigger the NAS procedure of the NAS layer. Inthis case, a specific value may be (pre)configured or provisioned to arange (e.g., the specific PPPP value or more).

III. In operation I described above, when the corresponding V2X messageis not the special message or not the message corresponding to thespecified PPPP value, the application layer may not provide but discardthe corresponding V2X message to the lower layer (e.g., the NAS layer orthe AS layer). In this case, operations I and II are not performed.

Method A) of Case I of Embodiment 2-1 described above may operatewithout operation I or II. That is, the NAS procedure may be performedonly by a triggering condition of the NAS procedure in the related artwithout delivering the special indication or specific PPPP value in theapplication layer.

A case in which Method B) described above (i.e., a case where the UEperforms not the Attach for the emergency bearer service but the NASprocedure) is performed will be described.

FIG. 14 is a diagram illustrating a method for performing V2Xcommunication over PC5 according to an embodiment of the presentinvention.

1. When the UE intends to perform the V2X communication over PC5, in thecase where the cell on which the UE camps transmits the V2X relatedinformation as the broadcast information, but does not broadcast theresource pool for transmitting the V2X message (i.e., in the case wherethe UE establishes the RRC connection with the eNB and cannot buttransmit the V2X message through the dedicated resource for the UE), theUE initiates not the Attach procedure for the emergency bearer servicebut the NAS procedure in order to switch to the EMM-CONNECTED mode. Inthis case, conditions for triggering the NAS procedure may be asfollows.

I. When the application layer (e.g., V2X layer) of the UE transmits theV2X message to the lower layer (i.e., NAS layer or AS layer), theinformation on the V2X message may be delivered. As an example of theinformation on the corresponding message, a special indication (or a V2Xservice indication) (e.g., ‘DENM’ or ‘emergency’ or ‘public safety’) ora specific PPPP value may be delivered.

For the aforementioned operation, in the case where the NAS layer or theRRC layer of the UE is using the emergency bearer service in the limitedservice state and has a capability for the V2X communication, the NASlayer or the RRC layer of the UE may inform the application layer of thecase where the NAS layer or the RRC layer of the UE is using theemergency bearer service in the limited service state and has thecapability for the V2X communication. As an example, when an NAS acceptmessage is received, such an announcement operation may be performed.

The application layer receiving such an operation may perform operationI described above. That is, the application layer may provide to thelower layer the information (a special indication or service indication)on the V2X message or provide the specific PPPP value while performingoperation I.

II. The NAS layer receiving the V2X message performs the above-describedNAS procedure.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the NAS procedure of the NAS layer may be triggered. In otherwords, only when the NAS layer has a (pre)configured or provisioned PPPPvalue and receives the corresponding PPPP value from the applicationlayer, the NAS procedure of the NAS layer may be triggered. In thiscase, a specific value may be (pre)configured or provisioned to a range(e.g., the specific PPPP value or more).

In this case, the interaction between the AS layer and the NAS layer mayoccur. For example, when the AS layer receives the special indication orPPPP value, the AS layer delivers the received special indication orPPPP value to the NAS layer to allow the NAS layer to trigger thecorresponding NAS procedure. Alternatively, the AS layer may deliver anindication that the V2X communication is required to the NAS layerinstead of delivering the received special indication or PPPP value asit is.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the NAS procedure of the NAS layer may be triggered. In otherwords, when the NAS layer has a (pre)configured or provisioned PPPPvalue and receives the corresponding PPPP value from the applicationlayer, the AS layer may trigger the NAS procedure of the NAS layer. Inthis case, a specific value may be (pre)configured or provisioned to arange (e.g., the specific PPPP value or more).

III. The UE performs not the Attach procedure for the emergency bearerservice but the NAS procedure. The NAS procedure may be defined as aservice request procedure in the related art or a new NAS procedure.Further, even as the NAS message, the service request message may beused or the new NAS message may be used.

IV. In operation I described above, when the corresponding V2X messageis not the special message or not the message corresponding to thespecified PPPP value, the application layer may not provide but discardthe corresponding V2X message to the lower layer (e.g., the NAS layer orthe AS layer). In this case, operations I and II are not performed.

2. When the UE in the limited service state performs the NAS procedure,the NAS layer of the UE generates the RRC establishment cause and/orindication and delivers the generated RRC establishment cause and/orindication to the AS layer of the UE together with the service requestmessage.

The AS layer of the UE uses the received RRC establishment cause and/orindication at the time of transmitting the RRC connection requestmessage.

I. The NAS layer of the UE may deliver the emergency call or a new cause(e.g., ‘public safety’) as the RRC establishment cause to the AS layerof the UE.

II. In this case, the NAS layer of the UE may deliver a ‘V2Xcommunication’ indication indicating that there is the V2X communicationcapability.

III. The RRC establishment cause or indication may be implemented asindividual values such as the ‘emergency call’ (or ‘public safetyservice’) and the ‘V2X communication’ and may be implemented as a thirdvalue (i.e., a single value) including meanings of the two values. Inthe latter case, as an example, the RRC establishment cause orindication may be implemented by an RRC establishment cause and/orindication such as an ‘emergency call with V2X communication capability’or a ‘public safety service with V2X communication capability’.

3. The AS layer of the UE includes the corresponding RRC establishmentcause and/or indication in the RRC Connection Request message (i.e., theRA message (msg) 3) and transmits the RRC establishment cause and/orindication to the eNB.

Thereafter, the AS layer of the UE receives an RRC Connection Setupmessage (i.e., RA msg 4) from the eNB. In addition, the AS layer of theUE transmits an RRC Connection Complete message to the eNB, therebycompleting the random access procedure.

4. The eNB receiving the RRC establishment cause and/or indication inthe RRC Connection Request message may confirm (check) that the UE hasthe V2X communication capability in the following method. In addition,the eNB confirms (checks) the V2X communication capability and storesthe confirmed (checked) V2X communication capability.

I. A method for confirming the V2X communication capability may beimplemented as follows.

A. When information indicating that there is the V2X communicationcapability is included in the indication (e.g., ‘V2X communication’)and/or the RRC establishment cause in the corresponding RRC connectionrequest message, the eNB may confirm (check) the V2X communicationcapability of the corresponding UE through the corresponding indicationand/or RRC establishment cause.

In this case, the eNB may perform a method of Embodiment 3 describedlater to verify (i.e., double check) the V2X communication capability ofthe corresponding UE.

B. When the information indicating that there is the V2X communicationcapability is not included in the indication (e.g., ‘V2X communication’)and/or the RRC establishment cause in the corresponding RRC connectionrequest message, the eNB may confirm the V2X communication capability ofthe corresponding UE through Embodiment 3 described later.

As illustrated in FIG. 14, the MME accepts the attach of the UE totransmit an Attach Accept message to the NAS layer of the correspondingUE. By receiving the Attach Accept message, the UE enters theEMM-CONNECTED mode and starts the emergency service. In FIG. 14, adetailed Attach procedure is omitted.

II. In the case where the corresponding RRC connection request isaccepted, when the UE indicates an ‘emergency call’ or ‘public safety’as the RRC establishment cause in step A above, the eNB may store thatthe corresponding UE is using the ‘emergency service’ or ‘publicsafety’.

Further, when it is confirmed in step B above that there is the V2Xcommunication capability for the corresponding UE, the eNB may storethat the corresponding UE has the V2X communication capability.

On the contrary, when the eNB rejects the RRC connection Request of theUE, the eNB may not store information on the corresponding UE.

Further, when the UE later switches to the EMM-IDLE or RRC-IDLE, the eNBmay delete memory information for the corresponding UE.

5. When the UE in the limited service state and the EMM-CONNECTED modeintends to perform the V2X communication over PCS, the UE transmits theSidelink UE information message to the eNB.

I. Triggering conditions for the Sidelink UE information messagetransmission of UE may be as follows.

A. When an application layer (i.e., V2X layer) of the UE transmits theV2X message to a lower layer (e.g., the NAS layer or the AS layer),information on the corresponding V2X message may be delivered. As anexample of the information on the corresponding message, a specialindication (or a V2X service indication) (e.g., ‘DENM’ or ‘emergency’ or‘public safety’) or a specific PPPP value may be delivered.

For operation A described above, in the case where the NAS layer or theRRC layer of the UE is using the emergency bearer service in the limitedservice state and has a capability for the V2X communication, the NASlayer or the RRC layer of the UE may inform the application layer of thecase where the NAS layer or the RRC layer of the UE is using theemergency bearer service in the limited service state and has thecapability for the V2X communication. As an example, when the attachaccept message is received, such an announcement operation may beperformed.

The application layer receiving such an operation may perform operationA described above. That is, the application layer may provide to thelower layer information (a special indication or service indication) onthe V2X message or provide the specific PPPP value while performingoperation A.

B. Even though the AS layer receiving the information or the specificPPPP value is currently in the limited service state, the AS layertransmits the Sidelink UE information message to the eNB.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the AS layer may transmit the Sidelink UE information messageto the eNB. In other words, only when the AS layer has a (pre)configuredor provisioned PPPP value and receives the corresponding PPPP value fromthe application layer, the AS layer may transmit the Sidelink UEinformation message to the eNB. In this case, a specific value may be(pre)configured or provisioned to a range (e.g., the specific PPPP valueor more).

C. In A above, when the corresponding V2X message is not the specialmessage or not the message corresponding to the specified PPPP value,the application layer may not provide but discard the corresponding V2Xmessage to the lower layer (e.g., the NAS layer or the AS layer). Inthis case, operations A and B described above are not performed.

II. In step 4 above, when I or II is not implemented (i.e., when the‘method for confirming the V2X communication capability of the UE’ isnot implemented), the following additional operation may be performed.

The UE may encapsulate in the corresponding Sidelink UE informationmessage the indication indicating that the ‘emergency service’ is usingand/or the special indication (or service indication) (e.g., ‘DENM’ or‘emergency’ or ‘public safety’).

6. The eNB may confirm the V2X communication capability of the UE or aninterest of the UE in the V2X communication through the receivedSidelink UE information message. In addition, when the V2X communicationcapability for the corresponding UE is confirmed, the eNB stores theconfirmed V2X communication capability.

Further, in this case, the eNB may perform Embodiment 3 in order toverify (double check) the V2X communication capability.

7. The eNB receiving the Sidelink UE information message may provide aV2X communication radio resource for the corresponding UE in thefollowing cases.

I. Case of confirming that the corresponding UE is in the ‘emergencycall’ or ‘public safety service’, or

II. Case of confirming that the corresponding UE is in the ‘emergencycall’ or ‘public safety service’ and confirms the V2X communicationcapability, or

III. Case of confirming that the corresponding UE is in the ‘emergencycall’ or ‘public safety service’ and confirms the V2X serviceauthorization. In this case, the V2X capability information may beadditionally provided from the MME to the eNB and the eNB may confirmthe V2X capability information.

Method B of Case 1 of Embodiment 2-1 described above may operate withoutstep 1-I or 1-II. That is, even though the application layer does notdeliver the special indication or the specific PPPP value to the lowerlayer, the NAS procedure may be performed only by the triggeringcondition of the NAS procedure in the related art.

Alternatively, Method B of Case I of Embodiment 2-1 described above mayoperate without step 5-I. That is, even though the application layerdoes not deliver the special indication or the specific PPPP value tothe lower layer, the Sidelink UE Information message may be transmittedonly by the transmission condition of the Sidelink UE Informationmessage in the related art.

Meanwhile, in the description of the present invention, a meaning that‘the eNB confirms the V2X communication capability’ includes a casewhere the MME provides V2X service authorization information to the eNBand the eNB checks whether the V2X service is authorized in the processof confirming the V2X communication capability when Embodiment 3 to bedescribed below is used.

(Case II) Operation when UE switches to RRC-CONNECTED and EMM-IDLE

FIG. 15 is a diagram illustrating a method for performing V2Xcommunication over PC5 according to an embodiment of the presentinvention.

1. When the UE intends to perform the V2X communication over PC5, in thecase where the cell on which the UE camps transmits the V2X relatedinformation as the broadcast information, but does not broadcast theresource pool for transmitting the V2X message (i.e., in the case wherethe UE establishes the RRC connection with the eNB and cannot buttransmit the V2X message through the dedicated resource for the UE), theUE initiates the RRC establishment procedure in order to switch to theRRC-CONNECTED state (and EMM-CONNECTED mode). In this case, conditionsfor triggering the RRC establishment procedure may be as follows.

I. Method of using the NAS procedure: Conditions for triggering the NASprocedure may be as follows.

A. When the application layer (e.g., V2X layer) of the UE transmits theV2X message to the lower layer (i.e., NAS layer or AS layer), theinformation on the V2X message may be delivered. As an example of theinformation on the corresponding message, a special indication (or a V2Xservice indication) (e.g., ‘DENM’ or ‘emergency’ or ‘public safety’) ora specific PPPP value may be delivered.

For the aforementioned operation, in the case where the NAS layer or theRRC layer of the UE has the capability for the V2X communication in thelimited service state, the NAS layer or the RRC layer of the UE mayannounce to the application layer the case where the NAS layer or theRRC layer of the UE has the capability for the V2X communication in thelimited service state. Such an operation may be performed when switchingto the limited service state.

The application layer receiving such an operation may perform operationA described above. That is, the application layer may provide to thelower layer the information (a special indication or service indication)on the V2X message or provide the specific PPPP value while performingoperation A.

B. The NAS layer receiving the V2X message performs the above-describedNAS procedure.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the NAS procedure of the NAS layer may be triggered. In otherwords, only when the NAS layer has a (pre)configured or provisioned PPPPvalue and receives the corresponding PPPP value from the applicationlayer, the NAS procedure of the NAS layer may be triggered. In thiscase, a specific value may be (pre)configured or provisioned to a range(e.g., the specific PPPP value or more).

In this case, the interaction between the AS layer and the NAS layer mayoccur. For example, when the AS layer receives the special indication orPPPP value, the AS layer delivers the received special indication orPPPP value to the NAS layer to allow the NAS layer to trigger thecorresponding NAS procedure. Alternatively, the AS layer may deliver anindication that the V2X communication is required to the NAS layerinstead of delivering the received special indication or PPPP value asit is.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the NAS procedure of the NAS layer may be triggered. In otherwords, when the NAS layer has a (pre)configured or provisioned PPPPvalue and receives the corresponding PPPP value from the applicationlayer, the AS layer may trigger the NAS procedure of the NAS layer. Inthis case, a specific value may be (pre)configured or provisioned to arange (e.g., the specific PPPP value or more).

C. When the corresponding V2X message is not the special message or notthe message corresponding to the specified PPPP value, the applicationlayer may not provide but discard the corresponding V2X message to thelower layer (e.g., the NAS layer or the AS layer). In this case,operations A and B described above are not performed.

D. The UE performs the NAS procedure. The NAS procedure may be definedas a service request procedure in the related art or a new NASprocedure. Further, even as the NAS message, the service request messagemay be used or the new NAS message may be used.

E. When the UE in the limited service state performs the NAS procedure,the NAS layer of the UE generates the RRC establishment cause and/orindication and delivers the generated RRC establishment cause and/orindication to the AS layer of the UE.

The AS layer of the UE uses the received RRC establishment cause and/orindication at the time of transmitting the RRC connection requestmessage.

The NAS layer of the UE may deliver the emergency call or a new cause(e.g., ‘public safety service’) as the RRC establishment cause to the ASlayer of the UE.

In this case, the NAS layer of the UE may deliver a ‘V2X communication’indication indicating that there is the V2X communication capability.

The RRC establishment cause or indication may be implemented asindividual values such as the ‘emergency call’ (or ‘public safetyservice’) and the ‘V2X communication’ and may be implemented as a thirdvalue (i.e., a single value) including meanings of the two values. Inthe latter case, as an example, the RRC establishment cause orindication may be implemented by an RRC establishment cause and/orindication such as an ‘emergency call with V2X communication capability’or a ‘public safety service with V2X communication capability’.

The AS layer of the UE includes the corresponding RRC establishmentcause and/or indication in the RRC Connection Request message (i.e., theRA message (msg) 3) and transmits the RRC establishment cause and/orindication to the eNB.

Thereafter, the AS layer of the UE receives an RRC Connection Setupmessage (i.e., RA msg 4) from the eNB. In addition, the AS layer of theUE transmits an RRC Connection Complete message to the eNB, therebycompleting the random access procedure.

F. In this case, the NAS message (e.g., the Service Request message orthe new NAS message) may not be delivered to the network (e.g., eNB orMME). In an implementation method, the NAS layer of the UE does notgenerate the NAS message or the NAS layer of the UE generates the NASmessage, but may not deliver the NAS message to the AS layer.

II. Method for performing an RRC connection establishment procedurewithout triggering the NAS procedure by the AS layer: The AS layer mayperform the RRC connection establishment procedure including the randomaccess procedure. The triggering conditions thereof may be as follows.

A. When the application layer (e.g., V2X layer) of the UE transmits theV2X message to the lower layer (i.e., NAS layer or AS layer), theinformation on the V2X message may be delivered. As an example of theinformation on the corresponding message, a special indication (or a V2Xservice indication) (e.g., ‘DENM’ or ‘emergency’ or ‘public safety’) ora specific PPPP value may be delivered.

For the aforementioned operation, in the case where the NAS layer or theRRC layer of the UE has the capability for the V2X communication in thelimited service state, the NAS layer or the RRC layer of the UE mayannounce to the application layer the case where the NAS layer or theRRC layer of the UE has the capability for the V2X communication in thelimited service state. Such an operation may be performed when switchingto the limited service state.

The application layer receiving such an operation may perform operationA described above. That is, the application layer may provide to thelower layer the information (a special indication or service indication)on the V2X message or provide the specific PPPP value while performingoperation A.

B. The AS layer performs the RRC connection establishment procedure.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the AS layer may perform the RRC connection establishmentprocedure. In other words, only when the AS layer has a (pre)configuredor provisioned PPPP value and receives the corresponding PPPP value, theRRC connection establishment may be performed. In this case, a specificvalue may be (pre)configured or provisioned to a range (e.g., thespecific PPPP value or more).

C. When the corresponding V2X message is not the special message or notthe message corresponding to the specified PPPP value, the applicationlayer may not provide but discard the corresponding V2X message to thelower layer (e.g., the NAS layer or the AS layer). In this case,operations A and B described above are not performed.

2. The AS layer receiving the RRC establishment cause and/or indicationperforms the RRC connection establishment procedure. The AS layerencapsulates the aforementioned value (i.e., the RRC establishment causeand/or indication) in the RRC Connection Request message (i.e., the RAmessage (msg) 3) and transmits the RRC establishment cause and/orindication.

Thereafter, the AS layer of the UE receives an RRC Connection Setupmessage (i.e., RA msg 4) from the eNB. In addition, the AS layer of theUE transmits an RRC Connection Complete message to the eNB, therebycompleting the random access procedure.

3. The eNB receiving the RRC establishment cause and/or indication inthe RRC Connection Request message may confirm (check) that the UE hasthe V2X communication capability in the following method. In addition,the eNB confirms (checks) the V2X communication capability and storesthe confirmed (checked) V2X communication capability.

When information indicating that there is the V2X communicationcapability is included in the indication (e.g., ‘V2X communication’)and/or the RRC establishment cause in the corresponding RRC connectionrequest message, the eNB may confirm (check) the V2X communicationcapability of the corresponding UE through the corresponding indicationand/or RRC establishment cause.

4. In the case where the corresponding RRC connection request isaccepted, when the UE indicates an ‘emergency call’ or ‘public safetyservice’ as the RRC establishment cause in step 3 above, the eNB maystore that the corresponding UE is using the ‘emergency service’ or‘public safety service’.

On the contrary, when the eNB rejects the RRC connection Request of theUE, the eNB may not store information on the corresponding UE.

Further, when the UE later switches to the EMM-IDLE or RRC-IDLE, the eNBmay delete memory information for the corresponding UE.

5. When the UE in the limited service state and the EMM-CONNECTED modeintends to perform the V2X communication over PCS, the UE transmits theSidelink UE information message to the eNB.

I. Triggering conditions for the Sidelink UE information messagetransmission of UE may be as follows.

A. When an application layer (i.e., V2X layer) of the UE transmits theV2X message to a lower layer (e.g., the NAS layer or the AS layer),information on the corresponding V2X message may be delivered. As anexample of the information on the corresponding message, a specialindication (or a V2X service indication) (e.g., ‘DENM’ or ‘emergency’ or‘public safety’) or a specific PPPP value may be delivered.

For operation A described above, in the case where the NAS layer or theRRC layer of the UE has the capability for the V2X communication in thelimited service state, the NAS layer or the RRC layer of the UE mayannounce to the application layer the case where the NAS layer or theRRC layer of the UE has the capability for the V2X communication in thelimited service state. As an example, such an announcement operation maybe performed when switching to the limited service state.

The application layer receiving such an operation may perform operationA described above. That is, the application layer may provide to thelower layer information (a special indication or service indication) onthe V2X message or provide the specific PPPP value while performingoperation A.

B. Even though the AS layer receiving the information or the specificPPPP value is currently in the limited service state, the AS layertransmits the Sidelink UE information message to the eNB.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the AS layer may transmit the Sidelink UE information messageto the eNB. In other words, only when the AS layer has a (pre)configuredor provisioned PPPP value and receives the corresponding PPPP value fromthe application layer, the AS layer may transmit the Sidelink UEinformation message to the eNB. In this case, a specific value may be(pre)configured or provisioned to a range (e.g., the specific PPPP valueor more).

C. In A above, when the corresponding V2X message is not the specialmessage or not the message corresponding to the specified PPPP value,the application layer may not provide but discard the corresponding V2Xmessage to the lower layer (e.g., the NAS layer or the AS layer). Inthis case, operations A and B described above are not performed.

II. In step 3 above, when I is not implemented (i.e., when the ‘methodfor confirming the V2X communication capability of the UE’ is notimplemented), the following additional operation may be performed.

The UE may encapsulate in the corresponding Sidelink UE informationmessage the special indication (or service indication) (e.g., ‘DENM’ or‘emergency’ or ‘public safety’).

6. The eNB may confirm the V2X communication capability of the UE or aninterest of the UE in the V2X communication through the receivedSidelink UE information message. In addition, when the V2X communicationcapability for the corresponding UE is confirmed, the eNB stores theconfirmed V2X communication capability.

7. The eNB receiving the Sidelink UE information message may provide aV2X communication radio resource for the corresponding UE in thefollowing cases.

I. Case of confirming that the corresponding UE is in the ‘emergencycall’ or ‘public safety service’, or

II. Case of confirming that the corresponding UE is in the ‘emergencycall’ or ‘public safety service’ and has the V2X communicationcapability.

The method of Case II of Embodiment 2-1 described above may operatewithout step 1-I-A or 1-I-B. That is, even though the application layerdoes not deliver the special indication or the specific PPPP value tothe lower layer, the NAS procedure may be performed only by thetriggering condition of the NAS procedure in the related art.

Alternatively, the method of Case II of Embodiment 2-1 described abovemay operate without step 1-II-A or 1-II-B. That is, even though theapplication layer does not deliver the special indication or thespecific PPPP value to the lower layer, the AS layer may perform the RRCconnection establishment procedure alone.

Embodiment 2-2

FIG. 16 is a diagram illustrating a method for performing V2Xcommunication over PC5 according to an embodiment of the presentinvention.

When a cell on which the UE camps sends V2X related information tobroadcasting information, but does not broadcast a resource pool for V2Xmessage transmission (i.e., when the UE establishes the RRC connectionwith the eNB and the corresponding UE has to transmit the V2X messagethrough a dedicated resource for itself), in the case where the UE inthe limited service state is in the EMM-IDLE, the corresponding UE mayoperate as follows.

I. When the application layer of the UE transmits the V2X message to thelower layer (i.e., NAS layer or V2X layer), information on thecorresponding V2X message may be delivered. As an example of theinformation on the corresponding message, a special indication (or a V2Xservice indication) (e.g., DENM or ‘emergency’ or ‘public safety’) or aspecific PPPP value may be delivered.

For the aforementioned operation, in the case where the NAS layer or theRRC layer of the UE has the capability for the V2X communication in thelimited service state, the NAS layer or the RRC layer of the UE mayannounce to the application layer the case where the NAS layer or theRRC layer of the UE has the capability for the V2X communication in thelimited service state. As an example, such an announcement operation maybe performed when switching to the limited service state.

The application layer receiving the announcement may perform operationI. That is, the application layer may provide to the lower layerinformation (a special indication or service indication) on the V2Xmessage or provide the specific PPPP value while performing operation I.

II. When the AS layer receiving the V2X message intends to perform theV2X communication over PC5, in the case where the eNB (base station)provides a next Tx resource pool, the AS layer may perform the V2Xcommunication over PC5 by using the Tx resource pool provided without aseparate process of requesting the Tx resource pool to the eNB in theEMM-IDLE (RRC-IDLE) state.

In this case, the Tx resource pool may be commTxPoolExceptionalbroadcasted by the eNB.

For example, as an additional condition, only when the sidelink UEinformation message corresponds to a specific V2X message type (e.g.,‘DENM’ or ‘emergency’ or ‘public safety’) which the network configuresto the UE, the AS layer may use the Tx resource pool. In other words,only when the AS layer has a (pre)configured or provisioned PPPP valueand receives the corresponding PPPP value, the AS layer may use the Txresource pool. In this case, a specific value may be (pre)configured orprovisioned to a range (e.g., the specific PPPP value or more).

III. When the corresponding V2X message is not the special message ornot the message corresponding to the specified PPPP value, theapplication layer may not provide but discard the corresponding V2Xmessage to the lower layer (e.g., the NAS layer or the AS layer) inoperation I. In this case, operations I and II are not performed.

Embodiment 2-2 described above may operate without step I or II. Thatis, even though the application layer does not deliver the specialindication or the specific PPPP value to the lower layer, when the ASlayer satisfies an execution condition of the V2X communication overPC5, the AS layer may perform the V2X communication over PC5.

According to the related art, when the UE is in the RRC-IDLE state, theUE may not use the commTxPoolExceptional. When the UE is in the RRC-IDLEstate, the UE may use the commTxPoolExceptional with some exceptionswhile performing an operation for switching to the RRC-CONNECTED state.However, in the limited service state, the UE may not perform locationregistration other than the Attach for the emergency bearer service. Asa result, the NAS procedure other than the Attach for the emergencybearer service is not triggered. Accordingly, a condition under whichthe commTxPoolExceptional may be used is not generated. In order tosolve such a problem, Embodiment 2-2 proposes such that even when the UEis in the RRC-IDLE state, the UE uses the commTxPoolExceptional in thelimited service state without performing the operation for switching tothe RRC-CONNECTED.

Embodiment 3

FIG. 17 is a diagram illustrating a method for performing V2Xcommunication over PC5 according to an embodiment of the presentinvention.

The MME may deliver to the eNB V2X communication related capabilityand/or authorization information of the UE.

In other words, the MME confirms only the capability of the UE todeliver the V2X capability of the UE to the eNB. Alternatively, the MMEmay confirm the capability of the UE and confirm whether thecorresponding service (i.e., V2X service) is authorized and then,deliver the authorization information to the eNB. For example, when theUE indicates the V2X capability and the UE is authorized to use the V2Xcommunication over PC5 based on subscription data, etc., the MME maydeliver to the eNB an indication “V2X services authorized”.

Embodiment 3-A

3. When the UE transmits to the eNB an RRC message including the AttachRequest message in order to initiate the Attach procedure for theemergency bearer service, the eNB may encapsulate the Attach Requestmessage for the emergency bearer service in an S1-AP initial UE messageand transmit the Attach Request message to the MME.

4. When the MME accepts an Attach request, the MME may transmit to theeNB as the Attach Accept message an S1-AP message (e.g., an S1-APDownlink NAS Transport message or an S1-AP Initial Context Setup Requestmessage). In this case, the following operation may be performed at thesame time.

-   -   When the UE has the capability or authorization for the V2X        communication, the V2X capability and/or authorization        information may be included in the S1-AP message and delivered        to the eNB. That is, the MME may encapsulate the Attach Accept        message with V2X capability and/or authorization in the S1-AP        message and transmit the Attach Accept message to the eNB.    -   Further, when the MME recognizes that the UE is in the limited        service state, the MME may encapsulate an indication for        announcing that the UE is in the limited service state in the        S1-AP message and transmit the indication to the eNB. That is,        the MME may encapsulate the Attach Accept message with the        indication for announcing that the UE is in the limited service        state in the S1-AP message and transmit the Attach Accept        message to the eNB. Alternatively, the eNB may implicitly        recognize the Attach Accept message through the method described        in the “processing of emergency call in limited service mode”        above.

Embodiment 3-B

3. When the UE sends the Sidelink UE information message to the eNB inorder to request the radio resource for the V2X communication (or whenthe eNB recognizes that ‘the UE is in a specific state’ at the sametime), the eNB may request to the MME the V2X communication relatedcapability and/or authorization information for the UE through the S1-APInitial UE message.

-   -   In this case, a case of recognizing ‘the corresponding UE is in        the specific state’ may correspond to a case where the        corresponding UE uses the emergency bearer service or a case of        recognizing that the UE is in the limited service state.    -   Alternatively, the case of recognizing ‘the corresponding UE is        in the specific state’ may correspond to a case where the        corresponding UE is the UE which is a UE specified thereby or        indicates a specific situation to the eNB (i.e., a case of        providing a capability or cause related thereto). An example of        information that the corresponding UE is the UE which is a UE        specified thereby or indicates the specific situation to the eNB        is as follows.    -   V2X communication    -   In the limited service state, the V2X communication is available    -   Emergency V2X message or public safety V2X message    -   Emergency call with V2X communication capability

4. When the MME receives a request for the V2X communication relatedcapability and/or authorization information, the MME may transmit to theeNB communication related capability and/or authorization informationthrough the S1-AP message (e.g., Downlink NAS Transport message or S1-APInitial Context Setup Request message).

-   -   When the UE has the capability or authorization for the V2X        communication, the V2X capability and/or authorization        information may be included in the S1-AP message and delivered        to the eNB.    -   Further, when the MME recognizes that the UE is in the limited        service state, the MME may encapsulate an indication for        announcing that the UE is in the limited service state in the        S1-AP message and transmit the indication to the eNB.        Alternatively, the eNB may implicitly recognize the Attach        Accept message through the method described in the “processing        of emergency call in limited service mode” above.

In Embodiment 3 described above, the S1-AP message which the eNBtransmits to the MME may be an initial UE message or a new S1-APmessage.

Further, the S1-AP message through which the MME transmits the V2Xcapability and/or authorization information to the eNB may be theInitial Context Setup Request message, the Downlink NAS Transportmessage, or the new S1-AP message. In this case, the S1-AP message maynot include UE context information for the V2 communicationauthorization.

Embodiment 4

The embodiment proposes the solution for Problem 3 described above.

Next, according to 3GPP TS 24.334, when the UE described in 3GPP TS24.386 is served by E-UTRAN, a precondition for the UE to perform theV2X communication over PC5 will be described.

When the UE receives the request from the upper layer to transmit theV2X message of the V2X service identified by the V2X service identifierby using the V2X communication over PC5, the UE performs the followingprocedure:

a) When the following condition is satisfied:

1) The UE is served by E-UTRAN;

2) The UE intends to use a radio resource (i.e., carrier frequency)provided by an E-UTRAN cell;

3) When the UE is served by the E-UTRAN, a registered PLMN belongs to aPLMN list authorized to use the V2X communication over PC5;

4) The V2X service identifier of the V2X service is included in the PLMNlist authorized for the V2X communication over PC5 or the UE isconfigured as a default destination Layer-2 identifier (ID) for the V2Xcommunication over PC5;

In this case, the UE operates as follows:

1) Requesting the radio resource for the V2 communication over PC5; and

2) performing transmission of the V2X communication over PC5

As described above, four conditions 1) to 4) are described. In thiscase, in the following cases, even though the UE served by E-UTRANsatisfies conditions 1), 2), and 4) above and does not satisfy condition3), the UE served by E-UTRAN may transmit the V2X communication overPC5.

A. Case in which the UE is in the limited service state,

B. Case in which the UE is performing the emergency call (service),

C. Case in which the UE is performing the emergency call (service) inthe initiated service state

That is, in any one case of the cases described in A to C above, eventhough the UE satisfies conditions 1), 2), and 4) above and does notsatisfy condition 3), the UE may transmit the V2X communication overPC5.

Embodiment 5

The embodiment proposes a solution for Problem 1.

In the scenario of Problem 1 above, proposed is a method in which theMME provides to the eNB the V2X service related context (i.e.,authorization information) of the corresponding UE.

As compared with Embodiment 3 described above, Embodiment 3 is a methodin which the eNB initiates the procedure, whereas Embodiment 5 proposesa method in which the MME initiates the procedure. The method in whichthe MME initiates the procedure may be divided into two followingmethods according to a case in which the MME makes a determination aloneor a case in which the MME interacts with the HSS.

When the eNB acquires the V2X service related context (i.e.,authorization information) of the corresponding UE by the method ofEmbodiment 5 to be described later, the eNB may allocate the resourcefor the V2X communication over PC5 for the corresponding UE.

Here, allocating the resource for the PC5 may be interpreted as variousmeanings. For example, in the case of a Mode 3 PC5 operation (i.e.,network scheduling resource allocation), a PC5 resource for transmittingthe V2X message may be allocated to the UE or the UE may be instructedto perform a Mode 4 PC5 operation (i.e., UE autonomous resourceselection).

Hereinafter, the embodiment may be implemented in the Attach proceduredefined in section 5.3.2.1 of 3GPP TS 23.401. In describing theembodiment, a detailed description of the Attach procedure is omittedand document 3GPP TS 23.401 V14.1.0 may be merged with thisspecification as a reference with respect to contents regarding adetailed Attach procedure.

Embodiment 5-1

Method in which the MME makes a decision singly and transmits the V2Xauthorization information to the eNB

FIG. 18 is a diagram illustrating a method for performing V2Xcommunication over PC5 according to an embodiment of the presentinvention.

1-2. The UE transmits the Attach Request message in order to perform theAttach procedure for the emergency bearer service. In this case, the UEmay include the following information in the Attach Request message.

A. The Attach Request message may include a UE network capability IE. Inthis case, since the UE has the capability for the V2X communicationover PC5, a V2X PC5 bit of the UE network capability IE may be set to“V2X communication over PC5 supported”. The information may indicatethat the UE is V2X communicable.

B. The Attach Request message may include an EPS attach type IE. The EPSattach type IE may be set to “EPS emergency attach”.

C. The Attach Request message (for the emergency bearer service) mayinclude a PDN Connectivity Request message. In this case, a request typeIE of the PDN Connectivity Request message may be set to “emergency”.

17. When the MME receiving the Attach Request message satisfies thefollowing conditions, the MME delivers to the ENB information that theV2X communication over PC5 is authorized through the S1-AP message. Forexample, the information that the V2X communication is authorized may bedelivered by setting a Vehicle UE bit of a V2X Service Authorized IE.Further, the MME may deliver through a new IE information indicatingthat the UE may perform the V2X communication over PCS and/or the UEperforms emergency attach and/or the UE has an emergency PDNconnectivity. As the S1-AP message for delivering the information, theInitial Context Setup Request message may be used and other (or new)S1-AP message may be used.

A. Case where the V2X PCS bit of the UE network capability IE of theAttach Request message is set to “V2X communication over PCS supported”(i.e., case where the MME recognizes that the UE is V2X enable), and/or

B. Case where the EPS attach type IE of the Attach Request message isset to “EPS emergency attach” or the request type IE of the PDNConnectivity Request message in the Attach Request message (for theemergency bearer service) is set to “emergency”

Embodiment 5-2

Method in which the MME Interacts with the HSS to Transmit the V2Xauthorization information to the eNB

FIG. 19 is a diagram illustrating a method for performing V2Xcommunication over PCS according to an embodiment of the presentinvention.

1. The UE transmits the Attach Request message in order to perform theAttach procedure for the emergency bearer service. In this case, the UEmay include the following information in the Attach Request message.

A. The Attach Request message may include a UE network capability IE. Inthis case, since the UE has the capability for the V2X communicationover PCS, a V2X PCS bit of the UE network capability IE may be set to“V2X communication over PCS supported”. The information may indicatethat the UE is V2X communicable.

B. The Attach Request message may include an EPS attach type IE. The EPSattach type IE may be set to “EPS emergency attach”.

C. The Attach Request message (for the emergency bearer service) mayinclude a PDN Connectivity Request message. In this case, a request typeIE of the PDN Connectivity Request message may be set to “emergency”.

8. When the Attach Request message includes (A and B) or (A and C) ofstep 1 above, the MME may transmit to the HSS an update location requestmessage including the following information.

I. The update location request message may include “emergency attach”and “V2X communication over PC5 supported”.

Alternatively, a new IE (i.e., single IE) may be defined and included,which includes two meanings of emergency attach and V2X communicationover PC5 supported. For example, the update location request message mayinclude emergency with V2X communication over PC5.

II. Only emergency information may be included. For example, “emergencyattach” may be applicable.

III. Only the V2X communication over PC5 information may be included.For example, the “V2X communication over PC5 information” may beapplicable.

11. The HSS receiving the update location request message may transmitan update location response message to the MME by setting the vehicle UEIE of the “V2X Services Authorized IE” based on the information includedin step 8.

Alternatively, a new IE may be defined and transmitted, which indicatesinformation (i.e., information indicating that the UE may perform theV2X communication over PC5) indicating that the UE is authorized for theV2X service.

-   -   In the aforementioned operation, the HSS confirms whether the        corresponding UE has the capability for the vehicle UE and only        when there is the capability for the corresponding vehicle UE, a        “V2X Services Authorized IE” may be included and transmitted.        When the corresponding UE has no capability for the vehicle UE,        the “V2X Services Authorized IE” may not be delivered to the MME        in step 11.    -   Even though the current PLMN of the UE is not included in the        PLMN list in which the UE in the subscriber information may use        the V2X communication over PC5, the HSS may provide to the MME        the information indicating that the UE is authorized for the V2X        service as described above.

17. When the MME that confirms the vehicle UE IE of the “V2X ServicesAuthorized IE” received from the HSS delivers to the eNB the informationthat the V2X communication over PC5 is authorized through the S1-APmessage. For example, the information that the V2X communication isauthorized may be delivered by setting a Vehicle UE bit of a V2X ServiceAuthorized IE. Further, the MME may deliver through a new IE informationindicating that the UE may perform the V2X communication over PC5 and/orthe UE performs emergency attach and/or the UE has an emergency PDNconnectivity. As the S1-AP message for delivering the information, theInitial Context Setup Request message may be used and other (or new)S1-AP message may be used.

FIG. 20 is a diagram illustrating a method for performing V2Xcommunication over PC5 according to an embodiment of the presentinvention.

Referring to FIG. 20, the base station (eNB) receives the Sidelink UEInformation message for requesting resource allocation for the V2Xcommunication over PC5 interface from the UE which is in the limitedservice state (S2001).

This step may correspond to step 5-II-B of Embodiment 1-1 above (seeFIG. 12), step 5-II-A of Case I of Embodiment 2-1 (see FIG. 14), or step5-I-B of Case II of Embodiment 2-1 (see FIG. 15).

The eNB checks whether the UE has the emergency PDN connection and has acapability to use the V2X communication and/or whether the UE isauthorized to perform the V2X communication (S2002).

This step may correspond to step 6 of Embodiment 1-1 (see FIG. 12), step6 of Case I of Embodiment 2-1 (see FIG. 14), or step 2 of Case II ofEmbodiment 6-1 (see FIG. 15).

The eNB may receive the RRC Connection Request message from the UEbefore step S2001 above. This step may correspond to step 2 ofEmbodiment 1-1 (see FIG. 12), step 3 of Case I of Embodiment 2-1 (seeFIG. 14), or step 2 of Case II of Embodiment 2-1 (see FIG. 15). Inaddition, when the RRC establishment cause set to the emergency calland/or V2X communication is included in the RRC connection requestmessage, the eNB may determine that the UE has the emergency PDNconnection. In this case, the emergency call and the V2X communicationmay be included as individual values or included as a single valueincluding meanings of both values.

In this case, when the eNB determines that the UE has the emergency PDNconnection (i.e., when the eNB receives the RRC establishment cause,etc.), the eNB may store information that the UE has the emergency PDNconnection. In addition, the information that the UE has the emergencyPDN connection may be deleted when the UE switches to the RRC-IDLEstate.

Further, when an indication indicating that the UE in the Sidelink UEInformation message uses the emergency service is received, the eNB maydetermine that the UE has the emergency PDN connection.

Further, as in Embodiment 3 above (see FIG. 17), the eNB may request tothe MME the V2X communication related authorization information for theUE. Upon receiving the information that the UE is authorized to performthe V2X communication from the MME in response thereto, the eNB maydetermine that the UE is authorized to perform the V2X communication.

In this case, when the eNB determines that the UE has the capability touse the V2X communication and the UE has the emergency PDN connection,the eNB may request the V2X communication related authorizationinformation for the UE to the MME. Further, upon receiving the SidelinkUE Information message from the UE, it may be implicitly regarded thatthe UE has the capability to use the V2X communication.

Further, as in Embodiment 5 above (see FIGS. 18 and 19), when the eNBreceives the S1-AP message including the information that the UE isauthorized to perform the V2X communication from the MME, the eNB maydetermine that the UE is authorized to perform the V2X communication.

In this case, as in Embodiment 5-1 (see FIG. 18), when the indicationthat the UE has the capability to use the V2X communication is includedin the Attach Request message for the emergency service transmitted fromthe UE, the MME may encapsulate the information that the UE isauthorized to perform the V2X communication in the S1-AP message aloneand transmit the information to the eNB.

Alternatively, as in Embodiment 5-2 (see FIG. 19), when the indicationthat the UE has the capability to use the V2X communication is includedin the Attach Request message for the emergency service transmitted fromthe UE, the MME requests the indication to the HSS to receive theinformation that the UE is authorized to perform the V2X communicationfrom the HSS and include the information that the UE is authorized toperform the V2X communication in the S1-AP message and transmit theinformation to the eNB.

When the UE has the emergency PDN connection and has the capability touse the V2X communication and/or the UE is authorized to perform the V2Xcommunication, the eNB allocates the resource for the V2X communicationto the UE (S2003).

This step may correspond to step 7 of Embodiment 1-1 (see FIG. 12), step7 of Case I of Embodiment 2-1 (see FIG. 14), or step 2 of Case II ofEmbodiment 7-1 (see FIG. 15).

Embodiment 6

The embodiment proposes a solution for Problem 4.

According to the related art, unlike ProSe, in the case of the V2Xcommunication over PC5, one or more frequencies may be configured. Inthis case, an operation performing method of the UE which is not servedby E-UTRAN is intended to be proposed.

In the embodiment, it is assumed that the UE performs up to thefollowing step according to the operation in the related art.

When the UE is not served by the E-UTRAN, the UE selects radioparameters to be used for the ProSe direct communication as follows.

-   -   When the UE may autonomously determine that the UE is positioned        in a geographical area and when the radio parameters for the        geographical area are provisioned to the UE, the UE selects the        radio parameters associated with the geographical area; or    -   In all other cases, the UE does not initiate the ProSe direct        communication.

Before initiating the ProSe direct communication, the UE checks whetherthe radio parameter selected by the lower layer may be used at a currentlocation without interference.

In the aforementioned description, when the UE uses the V2X service, theProSe is replaced with V2X and the ProSe direct communication isreplaced with the V2X communication over PC5 and adopted.

In this case, a result of checking interference by the lower layer ofthe UE which intends to perform the V2X communication over PC5 may beclassified into three following cases.

A. Case where the interference is not confirmed in all frequencies

B. Case where the interference is confirmed in all frequencies

C. Case where the interference is confirmed in some frequencies, but theinterference is not confirmed in the remaining some frequencies

In the case of A above, the UE may select one of the confirmedfrequencies and perform the following operation.

-   -   When the lower layer indicates that the usage does not cause the        interference, the UE may perform the ProSe direct communication        (or V2X communication over PC5).

In the case of B above, the UE may perform the following operation.

When the lower layer indicates that there is a cell that operates aprovisioned radio resource (i.e., carrier frequency) and thecorresponding cell belongs to a registered PLMN or a PLMN equivalent tothe registered PLMN and when the UE is authorized for the ProSe directcommunication (or V2X communication over PC5) in the corresponding PLMN,the UE may use the radio parameters indicated by the corresponding cell.

-   -   Otherwise, when the lower layer reports one or more PLMNs in the        provisioned radio resource (i.e., carrier frequency),

a) When the following conditions are satisfied:

1) when the PLMN reported by the lower layer is not the registered PLMNor the PLMN equivalent to the registered PLMN; and

2) at least one of the PLMNs reported by the lower layer is included inthe authorized PLMN list for the ProSe direct communication and providesthe radio resource for the ProSe direct communication.

In this case, the UE operates as follows:

1) in the EMM-IDLE mode, the UE performs PLMN selection triggered by theProSe direct communication; or

2) otherwise, when the UE is in the EMM-CONNECTED mode:

i) the UE performs a detach procedure and performs the PLMN selectiontriggered by the ProSe direct communication; or

ii) the UE does not initiate the ProSe direct communication.

The UE follows implementation of the UE with respect to whether toperform any operation of i) or ii) above.

b) Otherwise, the UE does not initiate the ProSe direct communication.

In the case of C above, the UE may perform the following operation.

The UE may select one of frequencies in which the interference is notconfirmed and perform the operation as in case A.

The operations of the UE for cases A, B, and C above are summarized asfollows.

1. When the V2X layer of the UE is “not served by E-UTRAN”, the V2Xlayer of the UE provides information on a radio parameter mapped to ageographical location to the lower layer (i.e., AS layer or RRC layer).

2. The lower layer (AS or RRC layer) that receives the informationchecks the interference in the corresponding radio parameter. As aresult, the lower layer operates as follows.

a. When the interference is not confirmed in all frequencies, the lowerlayer (AS or RRC layer) announces that there is no interference to theupper layer (i.e., V2X layer or NAS layer). When the upper layer (i.e.,V2X layer or NAS layer) receiving the information transmits the V2Xmessage to the lower layer (i.e., AS layer or RRC layer), the lowerlayer (i.e., AS layer or RRC layer) receiving the V2X message selectsone of frequencies without interference and transmits the correspondingV2X message.

b. When the interference is confirmed in all frequencies, the lowerlayer (AS or RRC layer) announces the PLMN list searched in thecorresponding frequency to the upper layer (i.e., V2X layer or NASlayer). The upper layer (i.e., V2X layer or NAS layer) performsoperation B above.

c. Case where the interference is confirmed in some frequencies, but theinterference is not confirmed in the remaining some frequencies

i. The lower layer (i.e., AS or RRC layer) announces that there is nointerference to the upper layer (i.e., V2X layer or NAS layer).

ii. When the upper layer (i.e., V2X layer or NAS layer) receiving theinformation transmits the V2X message to the lower layer (i.e., AS layeror RRC layer), the lower layer (i.e., AS layer or RRC layer) receivingthe V2X message selects one of frequencies without interference andtransmits the corresponding V2X message.

Embodiment 7

The embodiment proposes the solution for Problem 5 described above.

Embodiment 7-1 Method for Filtering V2X Message in UE

A method for filtering the V2X message may be performed by theapplication layer (i.e., V2X layer) or the lower layer (i.e., AS layeror RRC layer). Hereinafter, in describing the embodiment, it is assumedthat the PPPP value is larger, the priority is higher.

Option 1) Method for Filtering by Application Layer

1. In the case where the UE has the capability for the V2X communicationover PCS, when the NAS layer of the UE requests the PDN connection forthe emergency service, it is notified to the application layer (i.e.,V2X layer) responsible for the V2X communication over PC5 that theemergency service starts.

For example, an indication “emergency active” may be transmitted to theapplication layer (i.e., V2X layer). At the same time, the PPPPthreshold value is together delivered. The corresponding PPPP thresholdvalue may mean a value used in the emergency service operation and maybe a value provisioned to the UE.

A. Here, a case where the NAS layer of the UE requests the PDNconnection for the emergency service means a time of transmitting thePDN connectivity request message through the emergency PDN connection ora case of receiving the accept message to the PDN connectivity requestmessage through the emergency PDN connection.

B. In the aforementioned operation, the UE is in the EMM-CONNECTED mode.

C. The PPPP threshold value is a value configured in the network. Inthis case, the PPPP threshold value may be a PPPP threshold value usedonly when the emergency service occurs. That is, the network mayconfigure a PPPP threshold value used when the UE is not in an emergencyservice situation and a PPPP threshold value which may be used only whenthe UE is in the emergency service situation to the UE. In addition, itmay be determined whether the UE is in the emergency service situationand the PPPP threshold value suitable for each situation may be applied.

D. The network (e.g., eNB) may configure to the UE an indication ofprotecting the emergency service over the Uu (i.e., the radio interfacebetween the UE and the eNB). The lower layers (i.e., AS layer or RRClayer) receiving the indication delivers the indication to theapplication layer.

2. The application layer (i.e., V2X layer) receiving the indicationperforms the following operation whenever the V2X message is generated.

A. In the case where the PPPP threshold value is delivered in step 1above, when the PPPP value of the corresponding V2X message is largerthan the PPPP threshold value delivered in step 1, the corresponding V2Xmessage may be delivered to the lower layer (i.e., AS layer or RRClayer).

Otherwise, the corresponding V2X message may be discarded or kept. Inthis case, when the corresponding V2X message is kept, the correspondingV2X message may be discarded in the case where the corresponding V2Xmessage exceeds the delay budget of the corresponding V2X message.

B. In the case where the PPPP threshold value is not delivered in step 1above, only when the V2X message is a special message (e.g., ‘DENM’,‘emergency’, or ‘public safety’), the V2X message may be delivered tothe lower layer (i.e., AS layer or RRC layer).

Otherwise, the corresponding V2X message may be discarded or kept. Inthis case, when the corresponding V2X message is kept, the correspondingV2X message may be discarded in the case where the corresponding V2Xmessage exceeds the delay budget of the corresponding V2X message.

C. In the case where the indication for protecting the emergency serviceover the Uu is configured, when the emergency service is activeregardless of the PPPP value of the V2X message, the UE may discard orkeep the V2X message. In this case, when the corresponding V2X messageis kept, the corresponding V2X message may be discarded in the casewhere the corresponding V2X message exceeds the delay budget of thecorresponding V2X message.

C operation may be may be performed alone and performed together with Aor B above. In this case, when operation C operates together with A orB, the corresponding indication may indicate whether to apply A or B.That is, when the indication is configured, A or B may be applied.

When the emergency service is terminated, the NAS layer of the UEannounces that the emergency service is terminated to the applicationlayer (i.e., V2X layer). For example, an indication “emergency deactive”may be transmitted to the application layer (i.e., V2X layer). Theapplication layer (i.e., V2X layer) receiving the indication may performthe operation in the related art.

Option 2) Method for Filtering by Lower Layer

1. In the case where the UE has the capability for the V2X communicationover PC5, when the NAS layer of the UE requests the PDN connection forthe emergency service, it is notified to the lower layer (i.e., AS layeror RRC layer) that the emergency service starts.

For example, the indication “emergency active” may be transmitted to thelower layer (i.e., AS layer or RRC layer). At the same time, the PPPPthreshold value is together delivered. The corresponding PPPP thresholdvalue may mean a value used in the emergency service operation and maybe a value provisioned to the UE.

In this case, a bearer identifier for an emergency bearer may also beincluded.

A. Here, a case where the NAS layer of the UE requests the PDNconnection for the emergency service means a time of transmitting thePDN connectivity request message through the emergency PDN connection ora case of receiving the accept message to the PDN connectivity requestmessage through the emergency PDN connection.

B. In the aforementioned operation, the UE is in the EMM-CONNECTED mode.

C. The PPPP threshold value is a value configured in the network. Inthis case, the PPPP threshold value may be a PPPP threshold value usedonly when the emergency service occurs. That is, the network mayconfigure a PPPP threshold value used when the UE is not in an emergencyservice situation and a PPPP threshold value which may be used only whenthe UE is in the emergency service situation to the UE. In addition, itmay be determined whether the UE is in the emergency service situationand the PPPP threshold value suitable for each situation may be applied.

D. The network (e.g., eNB) may configure to the UE an indication ofprotecting the emergency service over the Uu.

2. The lower layer (i.e., AS layer or RRC layer) receiving theindication performs the following operation whenever the V2X message isgenerated.

A. In the case where the PPPP threshold value is delivered in step 1above, if the PPPP value of the corresponding V2X message is larger thanthe PPPP threshold value delivered in step 1, only when bothtransmission of the V2X message through the sidelink and transmission ofa protocol data unit (PDU) of the bearer corresponding to the emergencyservice over the Uu are transmitted at the same time, transmission ofthe corresponding V2X message is attempted.

Otherwise, the corresponding V2X message may be discarded or kept. Inthis case, when the corresponding V2X message is kept, the correspondingV2X message may be discarded in the case where the corresponding V2Xmessage exceeds the delay budget of the corresponding V2X message.

B. In the case where the PPPP threshold value is not delivered in step 1above, only when the V2X message is a special message (e.g., ‘DENM’,‘emergency’, or ‘public safety’), the V2X message may be delivered tothe lower layer (i.e., AS layer or RRC layer).

Otherwise, the corresponding V2X message may be discarded or kept. Inthis case, when the corresponding V2X message is kept, the correspondingV2X message may be discarded in the case where the corresponding V2Xmessage exceeds the delay budget of the corresponding V2X message.

i) For the above operation, the NAS layer may announce that theemergency service starts to the application layer in step 1. Theapplication layer (i.e., V2X layer) receiving the announcement maytransmit the information (e.g., ‘DENM’, ‘emergency’, or ‘public safety’)on the V2X message to the lower layer (i.e., AS layer or RRC layer)together with the V2X message.

C. In the case where the indication for protecting the emergency serviceover the Uu is configured, only when the emergency service is activeregardless of the PPPP value of the V2X message and both transmission ofthe V2X message through the sidelink and transmission of the PDU of thebearer corresponding to the emergency service over the Uu aretransmitted at the same time, the V2X message may be discarded or kept.

In this case, when the corresponding V2X message is kept, thecorresponding V2X message may be discarded in the case where thecorresponding V2X message exceeds the delay budget of the correspondingV2X message.

Alternatively, the power of the UE may be preferentially allocated totransmission of the PDU of the bearer corresponding to the emergencyservice over the Uu. Such an operation may be used alone and may beperformed together with operation A or B. In this case, when such anoperation is performed together with operation A or B, the correspondingindication may indicate whether to apply A or B. That is, when theindication is configured, A or B may be applied.

D. The following operations may be commonly performed with respect tooperations A, B, and C described above.

i) The lower layers (i.e., AS layer or RRC layer) receive the indicationthat the emergency service starts and the bearer identifier for theemergency bearer in step 1 above.

ii) When the lower layer (i.e., AS layer or RRC layer) receives the V2Xmessage, the PPPP value of the corresponding V2X message and thepriority of the emergency bearer are compared with each other, a servicehaving a high priority may be preferentially selected and transmitted.In this case, priority information mapped to each service (e.g.,emergency bearer service) or PPPP or information for determining whichservice is to be preferentially selected for each priority may bereceived from the network (e.g., eNB) or provisioned to the UE.

3. When the emergency service is terminated, the NAS layer of the UEannounces that the emergency service is terminated to the lower layer.For example, the indication “emergency deactive” may be transmitted tothe lower layer (i.e., AS layer or RRC layer). The lower layer (i.e., ASlayer or RRC layer) receiving the indication may perform the operationin the related art.

A. When i) of 2-B) above is implemented by the NAS layer operation, theoperation may be performed even in the application layer (i.e., V2Xlayer).

B. When the bearer identity for the emergency bearer is included in step1 above, the AS layer may know that the emergency service is terminatedthrough a fact that the corresponding emergency bearer isdeactivated/released. In this case, the operation of section 3 above maynot be performed.

Embodiment 7-2 Method for Indicating in RRC Message by RRC Layer of UE

1. In the case where the UE has the capability for the V2X communicationover PC5, when the NAS layer of the UE requests the PDN connection forthe emergency service, it is notified to the lower layer (i.e., AS layeror RRC layer) that the emergency service starts.

For example, the indication “emergency active” may be transmitted to thelower layer (i.e., AS layer or RRC layer). In this case, the beareridentity for the emergency bearer may also be included.

A. Here, a case where the NAS layer of the UE requests the PDNconnection for the emergency service means a time of transmitting thePDN connectivity request message through the emergency PDN connection ora case of receiving the accept message to the PDN connectivity requestmessage through the emergency PDN connection.

B. In the aforementioned operation, the UE is in the EMM-CONNECTED mode.

2. The lower layer (i.e., AS layer or RRC layer) receiving theindication performs the following operation.

A. The RRC message (e.g., Sidelink UE information message or sidelinkBSR) includes the indication for announcing that the emergency servicestarts.

For example, the indication “emergency active” may be included. In thiscase, the bearer identity for the emergency bearer or a logical channelidentifier (ID) may also be included.

B. The eNB receiving the RRC message performs the resource allocationbased on the bearer identity for the emergency bearer or logical channelidentifier (ID).

i. Here, in a resource allocating operation, LTE-Uu for thecorresponding emergency bearer may be processed preferentially over theV2X communication over PC5 or the resource allocating operation may beperformed by considering the PPPP value of the V2X message and theinformation on the emergency bearer.

ii. When the lower layer (i.e., AS layer or RRC layer) receives the V2Xmessage, the PPPP value of the corresponding V2X message and thepriority of the emergency bearer are compared with each other, a servicehaving a high priority may be preferentially selected and transmitted.In this case, priority information mapped to each service (e.g.,emergency bearer service) or PPPP or information for determining whichservice is to be preferentially selected for each priority may bereceived from the network (e.g., eNB) or provisioned to the UE.

3. When the emergency service is terminated, the NAS layer of the UEannounces that the emergency service is terminated to the lower layer.For example, the indication “emergency deactive” may be transmitted tothe lower layer (i.e., AS layer or RRC layer).

4. The lower layer (i.e., AS layer or RRC layer) receiving theindication may encapsulate the indication that the emergency service isterminated in the RRC message (e.g., Sidelink UE information message orSidelink BSR). For example, the indication “emergency deactive” may beincluded. In this case, the bearer identity for the emergency bearer orthe logical channel ID may also be included. Thereafter, the lower layer(i.e., AS layer or RRC layer) may perform the operation in the relatedart.

A. When the bearer identity for the emergency bearer is included in step1 above, the AS layers of the UE and the eNB may know that the emergencyservice is terminated through a fact that the corresponding emergencybearer is deactivated/released. In this case, the operations 3 and 4above may not be performed.

Embodiment 8

The embodiment proposes the solution for Problem 6 described above.

As mentioned in Problem 6) above, the RRC layer of the UE needs to knowthe following information in order to perform prioritization of theemergency PDN connection and the V2X communication over PC5.

1) whether the UE has the emergency PDN connection

2) whether the communication over the emergency PDN connection needs tobe prioritized over the V2X communication over the PC5 reference pointbased on regional/national regulatory requirements and operator policies

The embodiment intends to propose the following operations.

Option 1) Method in which the upper layer (i.e., the NAS layer of the UEor the V2X layer of the UE) of the UE informs the lower layers (i.e.,the AS layer of the UE (e.g., the RRC layer of the UE and/or the MAClayer of the UE))

1. The UE has the active emergency PDN connection. In addition,

2. The communication over the emergency PDN connection needs to beprioritized over the V2X communication over the PC5 reference pointbased on regional/national regulatory requirements and operatorpolicies.

When Conditions 1 and 2 above are satisfied, the upper layer (i.e., theNAS layer of the UE or the V2X layer of the UE) delivers the followinginformation to the lower layers (i.e., the AS layer of the UE (e.g., theRRC layer of the UE and/or the MAC layer of the UE)).

I. ‘Emergency call’ indication and/or bearer identity for emergencybearer service

Here, the ‘emergency call’ indication is an indication for announcingthat the emergency PDN connection is established.

II. ‘Emergency prioritized over PC5’ indication

Here, the ‘emergency prioritized over PC5’ indication is an indicationfor announcing the following configuration.

-   -   The communication over the emergency PDN connection needs to be        prioritized over the V2X communication over the PC5 reference        point based on regional/national regulatory requirements and        operator policies.

When the upper layer delivers such an indication to the lower layers,the lower layer may operate as follows.

-   -   When an operation of establishing the emergency PDN connection        is performed, in the case where the upper layer announces such        an indication to the lower layers, the upper layer may deliver        the corresponding indication together with the corresponding NAS        message (e.g., NAS message used in Attach for the emergency PDN        connection or the PDN connection for the emergency bearer        services, e.g., Attach Request message or PDN Connectivity        Request message).    -   When such an indication is delivered after the emergency PDN        connection is established, a separate indication may be        delivered after the emergency PDN connection is established.    -   Indications I) and II) described above may be together delivered        or only any one of indications I) and II) may be delivered.    -   When the aforementioned indication is delivered, the UE may be        in the EMM-CONNECTED mode. That is, only when the UE is in the        EMM-CONNECTED mode, the aforementioned indication may be        transmitted. Further, when generally applied, the UE may be in        the EMM-IDLE mode.

Option 2) Method in which the eNB informs the lower layers (i.e., ASlayer (e.g., RRC layer of the UE and/or MAC layer of the UE) of the UE

1. The UE has the active emergency PDN connection. In addition,

2. The communication over the emergency PDN connection needs to beprioritized over the V2X communication over the PC5 reference pointbased on regional/national regulatory requirements and operatorpolicies.

When Conditions 1 and 2 above are satisfied, the eNB delivers thefollowing information to the UE.

I. ‘Emergency call’ indication and/or bearer identity for emergencybearer service (or logical channel ID (LCID))

Here, the ‘emergency call’ indication is an indication for announcingthat the emergency PDN connection is established.

II. ‘Emergency prioritized over PC5’ indication

Here, the ‘emergency prioritized over PC5’ indication is an indicationfor announcing the following configuration.

-   -   The communication over the emergency PDN connection needs to be        prioritized over the V2X communication over the PC5 reference        point based on regional/national regulatory requirements and        operator policies.

When the eNB delivers such an indication to the UE, the eNB may operateas follows.

-   -   Indications I) and II) described above may be together delivered        or only any one of indications I) and II) may be delivered.    -   Indication I) described above may be delivered to the UE as a        dedicated message.

Commonly to option 1 and option 2 described above, the lower layers(i.e., AS layer (e.g., RRC layer of the UE and/or MAC layer of the UE))receiving the indication may recognize a bearer corresponding to theemergency PDN connection and a message (i.e., uplink transmission over aUu interface) generated in the corresponding bearer may be prioritized(or scheduled) over the message generated for the V2X communication overPC5.

More specifically, when the uplink transmission (i.e., transmission overthe Un interface) overlaps with V2X sidelink transmission (i.e.,transmission of the V2X communication over PC5) in the time domainwithin the same frequency, if a PPPP value of a sidelink MAC PDU islower than a (pre)configured PPPP threshold value, the UE prioritizesthe sidelink transmission over the uplink transmission.

However, when the uplink transmission is prioritized by the upper layer(i.e., NAS layer of the UE or V2X layer of the UE) (i.e., whenindications I) and/or II) are transmitted from the upper layer asdescribed above), the UE prioritizes the uplink transmission over anyV2X sidelink transmission (i.e., regardless of the PPPP value of thesidelink MAC PDU).

FIG. 21 is a diagram illustrating a method for performing V2Xcommunication over PC5 according to an embodiment of the presentinvention.

Referring to FIG. 21, the UE (in particular, the lower layer of the UE)receives a request for transmission of the V2X message from the upperlayer (S2101).

That is, the upper layer may request the UE to transmit the V2X messageof a V2X service identified by a V2X service identifier by using the V2Xcommunication over PC5.

In this case, the request from the upper layer may include:

a) V2X message;

b) V2X service identifier of the V2X service for the V2X message;

c) Data type in the V2X message (Internet protocol (IP) or non-IP);

d) When the V2X message includes non-IP data, an indication for settinga non-IP type field of a non-IP type PDU to a value corresponding to aV2X message family; and

e) V2X message priority

When receiving the request for transmitting the V2X message from theupper layer in S2101, the UE may request the radio resource for the V2Xcommunication over the PC5 interface to the eNB (S2102).

Here, step S2012 may be performed when the following conditions aresatisfied.

1) The UE is “served by E-UTRAN”

2) The UE intends to use a radio resource (i.e., carrier frequency)provided by an E-UTRAN cell

3) When the UE is served by the E-UTRAN, a registered PLMN belongs to aPLMN list authorized to use the V2X communication over PC5

4) The V2X service identifier of the V2X service is included in the PLMNlist authorized for the V2X communication over PC5 or the UE isconfigured as a default destination Layer-2 identifier (ID) for the V2Xcommunication over PC5

Alternatively, when receiving the request for transmitting the V2Xmessage from the upper layer in S2101, the UE may select the radioresource for the V2X communication over PC5 interface (S2103).

Here, step S2013 may be performed when the following conditions aresatisfied.

1) The UE:

A) “not served by E-UTRAN”; or

B) is in the EMM-IDLE mode and the limited service state, when the UE isin the limited service state, the UE corresponds to any one of thefollowings cases;

i) when the UE may not find the suitable cell in the selected PLMN;

ii) a case where the UE receives an ATTACH REJECT message, a TRACKINGAREA UPDATE REJECT message, or a SERVICE REJECT message including EMMcause #11 “PLMN not allowed” or the UE receives a LOCATION UPDATINGREJECT message, a GPRS ATTACH REJECT message, or a ROUTING AREA UPDATEREJECT message including EMM cause #11 “PLMN not allowed”; or

iii) a case where the UE receives the ATTACH REJECT message or TRACKINGAREA UPDATE REJECT message or SERVICE REJECT message including EMM cause#7 “EPS services not allowed” or a case where the UE receives theLOCATION UPDATING REJECT message or GPRS ATTACH REJECT message orROUTING AREA UPDATE REJECT message or SERVICE REJECT message includingEMM cause #7 “EPS services not allowed”;

2) When the UE is not served by the E-UTRAN, the UE is authorized to usethe V2X communication over PC5

3) The V2X service identifier of the V2X service is included in a listof the V2X services authorized for the V2X communication over PC5 or theUE is configured as a default destination Layer-2 identifier (ID) forthe V2X communication over PC5

The UE performs the transmission for the V2X communication over the PC5interface (S2102).

That is, the UE may perform the transmission of the V2X communicationover the PC5 interface on the radio resource allocated from the eNB instep S2102 or perform the transmission of the V2X communication over thePC5 interface on the radio resource selected in step S2103.

In this case, when receiving indication I) and/or indication II)described above from the upper layer, the message (i.e., uplinktransmission over the Uu interface) generated in the bearercorresponding to the emergency PDN connection may be prioritized (orscheduled) over the message generated for the V2X communication over PC5by the lower layer.

In other words, when the uplink transmission is prioritized by the upperlayer (i.e., NAS layer of the UE or V2X layer of the UE) (i.e., whenindications I) and/or II) are transmitted from the upper layer asdescribed above), the UE prioritizes the uplink transmission over anyV2X sidelink transmission (i.e., regardless of the PPPP value of thesidelink MAC PDU).

As described above, indication I) and/or indication II) may be deliveredtogether with the non-access stratum (NAS) message for establishing theemergency PDN connection or delivered separately from the non-accessstratum (NAS) message for establishing the emergency PDN connection.

Meanwhile, when the conditions exemplified in steps S2102 and S2103above are not satisfied, the UE may not perform the V2X communicationover PC5.

Meanwhile, in the description of the present invention, for convenienceof description, the V2X communication among the V2X services isprimarily described, but the operation of the present invention may besimilarly applied even to all V2X services including the V2X discovery.

Further, in the description of the present invention, for convenience ofdescription, the V2X communication is primarily described, but thepresent invention may be applied to all of data transmission andreception over PC5 interface (i.e., sidelink).

Further, combinations of one or more embodiments described above may betogether implemented and used. In addition, in the procedure describedin each embodiment, all of respective steps may not be performed andonly some steps may be performed. That is, performing each step may beperformed independently from performing a previous or subsequent step.In other words, the next step may be performed without performing theprevious step.

The ‘limited service state’ used in the present invention may mean onlya state of satisfying the following conditions described in 3GPP TS24.386 and 3GPP TS 23.122.

i) when the UE may not find the suitable cell in the selected PLMN;

ii) a case where the UE receives an ATTACH REJECT message, a TRACKINGAREA UPDATE REJECT message, or a SERVICE REJECT message including EMMcause #11 “PLMN not allowed” or the UE receives a LOCATION UPDATINGREJECT message, a GPRS ATTACH REJECT message, or a ROUTING AREA UPDATEREJECT message including EMM cause #11 “PLMN not allowed”; or

iii) a case where the UE receives the ATTACH REJECT message or TRACKINGAREA UPDATE REJECT message or SERVICE REJECT message including EMM cause#7 “EPS services not allowed” or a case where the UE receives theLOCATION UPDATING REJECT message or GPRS ATTACH REJECT message orROUTING AREA UPDATE REJECT message or SERVICE REJECT message includingEMM cause #7 “EPS services not allowed”;

That is, the operation of the present invention may not be applied to acase where the UE is in the limited service state due to other reasonsother than the aforementioned conditions.

In the description of the present invention, in the step of deliveringthe ‘emergency’ related indication, an indication for announcing thatthe UE is in the limited service state may be delivered together withthe ‘emergency’ related indication or the indication for announcing thatthe UE is in the limited service state may be delivered instead of the‘emergency’ related indication.

Here, as an example of the ‘emergency’ related indication, the‘emergency call’ may be applicable.

Further, the delivery may be a delivery between the layers (i.e.,application layer, V2X layer, NAS layer, and AS layer (e.g., RRC layer))in the UE or a delivery between network entities (i.e., UE, eNB, andMME).

According to the present invention, even when the UE is in the limitedservice state, the UE may perform the V2X communication. As a result, itis possible to cope with a load safety situation or a public safetyrelated situation.

According to the related art, it is impossible for the UE in the limitedservice state and the EMM-CONNECTED state to perform the V2Xcommunication over PCS.

Specifically, even though the UE in the limited service state and theEMM-CONNECTED state requests the resource for the V2X communicationthrough the sidelink UE information, since the eNB does not haveauthorization information for the UE, the eNB may not accept therequest.

However, according to Embodiment 1-1 of the present invention, aprocedure in which the UE requests the resource for the V2Xcommunication over PC5 and the eNB determines and decides the requestedresource is proposed, and as a result, it is possible to perform the V2Xcommunication over PC5 of the UE.

Further, according to Embodiment 1-2 of the present invention, the UEmay perform the V2X communication over PC5 by using the Tx resource poolwithout request to the eNB.

According to the related art, when the cell on which the UE in thelimited service state and the EMM-IDLE state camps sends the V2X relatedinformation as the broadcast information, but does not broadcast theresource pool for transmission (i.e., when the UE establishes the RRCconnection with the eNB and cannot but transmit the V2X message throughthe dedicated resource for the UE), it is impossible to perform the V2Xcommunication over PC5.

However, according to Embodiment 2-1 of the present invention, when thecell on which the UE in the limited service state and the EMM-IDLE statecamps sends the V2X related information as the broadcast information,but does not broadcast the resource pool for transmission (i.e., whenthe UE establishes the RRC connection with the eNB and cannot buttransmit the V2X message through the dedicated resource for the UE), inthe case where it is necessary to perform the V2X communication overPC5, it is possible to perform the V2X communication over PC5 throughthe following methods.

I. Method for switching to EMM-CONNECTED

A. Performing attach for emergency bearer service [Embodiment 2-1-CaseI-A]

B. Performing NAS procedure other than attach for emergency bearerservice [Embodiment 2-1-Case I-B]

II. Method for switching to RRC-CONNECTED (and EMM-IDLE)

A. Together with NAS procedure (through step 2-I)

B. Without NAS procedure (through step 2-II)

In the case of the corresponding procedure, the RRC procedure (i.e., RRCconnection establishment procedure) is performed without triggering theNAS procedure to reduce an unnecessary signaling or interaction.

Further, according to Embodiment 2-2 of the present invention, the UEmay perform the V2X communication over PC5 by using the Tx resource poolwithout request to the eNB.

Further, Embodiment 7 of the present invention may be applied even to acase where a radio channel is congested. For example, when the radiochannel is congested and it is thus necessary to limit a PC5 resource,the network may encapsulate and transmit the PPPP threshold value to asystem information block (SIB). The UE that receives the PPPP thresholdvalue may operate by the method proposed Embodiment 7 above. When theapplication layer performs filtering in Embodiment 7, the AS layer ofthe UE receiving the PPPP threshold value may inform the applicationlayer. When the lower layer performs filtering in Embodiment 7, the ASlayer of the UE receiving the PPPP threshold value may directly applyand operate. The AS layer of the UE may exchange the received PPPPthreshold value with the NAS layer.

Overview of Devices to which Present Invention is Applicable

FIG. 22 illustrates a block diagram of a communication apparatusaccording to an embodiment of the present invention.

Referring to FIG. 23, a wireless communication system includes a networknode 2210 and multiple user equipments 2220.

The network node 2210 includes a processor 2211, a memory 2212, and acommunication module 2213. The processor 2211 implements a function, aprocess, and/or a method which are proposed in FIGS. 1 to 21 above.Layers of a wired/wireless interface protocol may be implemented by theprocessor 2211.

The memory 2212 is connected with the processor 2211 to store variouspieces of information for driving the processor 2211. The communicationmodule 2213 is connected with the processor 2211 to transmit and/orreceive a wired/wireless signal. An example of the network node 2210 maycorrespond to a base station, MME, HSS, SGW, PGW, SCEF, SCS/AS, etc. Inparticular when the network node 2210 is the base station, thecommunication module 2213 may include a radio frequency (RF) unit fortransmitting/receiving the wireless signal.

The UE 2220 includes a processor 2221, a memory 2222, and acommunication module (or RF unit) 2223. The processor 2221 implements afunction, a process, and/or a method which are proposed in FIGS. 1 to 21above. The layers of the wireless interface protocol may be implementedby the processor 2221. In particular, the processor may include an NASlayer and an AS layer. The memory 2222 is connected with the processor2221 to store various pieces of information for driving the processor2221. The communication module 2223 is connected with the processor 2221to transmit and/or receive the wireless signal.

The memories 2212 and 2222 may be positioned inside or outside theprocessors 2211 and 2221 and connected with the processors 2211 and 2221by various well-known means. Further, the network node 2210 (when thenetwork node 2220 is the base station) and/or the UE 2220 may have asingle antenna or multiple antennas.

FIG. 23 illustrates a block diagram of a communication apparatusaccording to an embodiment of the present invention.

In particular, FIG. 23 is a diagram more specifically illustrating theUE of FIG. 22 above.

Referring to FIG. 23, the UE may be configured to include a processor(or a digital signal processor (DSP) 2310, an RF module (or RF unit)2335, a power management module 2305, an antenna 2340, a battery 2355, adisplay 2315, a keypad 2320, a memory 2330, a subscriber identificationmodule (SIM) card 2325 (this component is optional), a speaker 2345, anda microphone 2350. The UE may also include a single antenna or multipleantennas.

The processor 2310 implements a function, a process, and/or a methodwhich are proposed in FIGS. 1 to 21 above. Layers of a wirelessinterface protocol may be implemented by the processor 2310.

The memory 2330 is connected with the processor 2310 to storeinformation related to an operation of the processor 2310. The memory2330 may be positioned inside or outside the processor 2310 andconnected with the processor 2310 by various well-known means.

A user inputs command information such as a telephone number or the likeby, for example, pressing (or touching) a button on the keypad 2320 orby voice activation using the microphone 2350. The processor 2310receives such command information and processes to perform appropriatefunctions including dialing a telephone number. Operational data may beextracted from the SIM card 2325 or the memory 2330. In addition, theprocessor 2310 may display command information or drive information onthe display 2315 for the user to recognize and for convenience.

The RF module 2335 is connected with the processor 2310 to transmitand/or receive an RF signal. The processor 2310 transfers the commandinformation to the RF module 2335 to initiate communication, forexample, to transmit wireless signals constituting voice communicationdata. The RF module 2335 is constituted by a receiver and a transmitterfor receiving and transmitting the wireless signals. The antenna 2340functions to transmit and receive the wireless signals. Upon receivingthe wireless signals, the RF module 2335 may transfer the signal forprocessing by the processor 2310 and convert the signal to a baseband.The processed signal may be converted into to audible or readableinformation output via the speaker 2345.

In the embodiments described above, the components and the features ofthe present invention are combined in a predetermined form. Eachcomponent or feature should be considered as an option unless otherwiseexpressly stated. Each component or feature may be implemented not to beassociated with other components or features. Further, the embodiment ofthe present invention may be configured by associating some componentsand/or features. The order of the operations described in theembodiments of the present invention may be changed. Some components orfeatures of any embodiment may be included in another embodiment orreplaced with the component and the feature corresponding to anotherembodiment. It is apparent that the claims that are not expressly citedin the claims are combined to form an embodiment or be included in a newclaim by an amendment after the application.

The embodiments of the present invention may be implemented by hardware,firmware, software, or combinations thereof. In the case ofimplementation by hardware, according to hardware implementation, theexemplary embodiment described herein may be implemented by using one ormore application specific integrated circuits (ASICs), digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, micro-controllers, microprocessors,and the like.

In the case of implementation by firmware or software, the embodiment ofthe present invention may be implemented in the form of a module, aprocedure, a function, and the like to perform the functions oroperations described above. A software code may be stored in the memoryand executed by the processor. The memory may be positioned inside oroutside the processor and may transmit and receive data to/from theprocessor by already various means.

It is apparent to those skilled in the art that the present inventionmay be embodied in other specific forms without departing from essentialcharacteristics of the present invention. Accordingly, theaforementioned detailed description should not be construed asrestrictive in all terms and should be exemplarily considered. The scopeof the present invention should be determined by rational construing ofthe appended claims and all modifications within an equivalent scope ofthe present invention are included in the scope of the presentinvention.

INDUSTRIAL APPLICABILITY

An example is applied to the 3GPP LTE/LTE-A system is describedprimarily, but it is possible to apply the RRC connection method tovarious wireless communication systems, in particular, a 5 generation(G) system in addition to the 3GPP LTE/LTE-A system.

What is claimed is:
 1. A method for performing, by a user equipment(UE), vehicle-to-everything (V2X) communication over a PC5 interface ina wireless communication system, the method comprising: receiving, froman upper layer, a request message for transmitting a V2X message;requesting, to a base station, a radio resources for V2X communicationover PC5 or selecting the radio resources for the V2X communication overPC5; and performing transmission of the V2X communication over PC5,wherein if the UE has an emergency packet data network (PDN) connection,the UE shall send an indication to the lower layers to prioritizetransmission over the emergency PDN connection as compared totransmission of the V2X communication over PC5.
 2. The method of claim1, further comprising: if the indication is received, the transmissionthrough the emergency PDN connection is prioritized over thetransmission of the V2X communication over PC5.
 3. The method of claim1, wherein the indication is transmitted separately from a non-accessstratum (NAS) message for establishing the emergency PDN connection. 4.The method of claim 1, wherein the indication is transmitted togetherwith the non-access stratum (NAS) message for establishing the emergencyPDN connection.
 5. The method of claim 1, wherein the request messagefor transmitting the V2X message includes a V2X message, a V2X serviceidentifier of a V2X service for the V2X message, a data type in the V2Xmessage, and a V2X message priority.
 6. The method of claim 1, whereinwhen the UE is serviced by an Evolved Universal Terrestrial Radio AccessNetwork (E-UTRAN), the UE intends to use the radio resources provided bya cell of the E-UTRAN, and a Public Land Mobile Network (PLMN) in whichthe UE is registered belongs to a PLMN list authorized to use the V2Xcommunication via the PC5, the radio resources for the V2X communicationvia the PC5 interface is requested to the base station.
 7. The method ofclaim 1, wherein if the UE is not serviced by the E-UTRAN and the UE isauthorized to use the V2X communication over PC5, the radio resourcesfor the V2X communication over PC5 is selected.
 8. The method of claim1, wherein if the UE is in an EPS Mobility Management (EMM)-IDLE modeand in a limited service state, the radio resources for the V2Xcommunication over PC5 is selected.
 9. The method of claim 1, wherein anidentifier of a bearer corresponding to the emergency PDN connection istransmitted together with the indication.
 10. The method of claim 1,wherein only when the UE is in an EPS Mobility Management-CONNECTED(EMM) mode, the indication is transmitted.
 11. A user equipment (UE)performing vehicle-to-everything (V2X) communication over a PC5interface in a wireless communication system, the UE comprising: acommunication module; at least one processor; and at least one computermemory operably connectable to the at least one processor and storinginstructions that, when executed by the at least one processor, performoperations comprising: receiving, via the communication module from anupper layer, a request message for transmitting a V2X message,requesting, via the communication module to a base station, a radioresources for V2X communication over PC5 or selecting the radioresources for the V2X communication over PC5; and performingtransmission of the V2X communication over PC5, wherein if the UE has anemergency packet data network (PDN) connection, the UE shall send anindication to the lower layers to prioritize transmission over theemergency PDN connection as compared to transmission of the V2Xcommunication over PC5.